diff --git a/README.rst b/README.rst
index abab13eb..3a77b607 100644
--- a/README.rst
+++ b/README.rst
@@ -35,7 +35,7 @@
 .. |Tracking| image:: https://img.shields.io/badge/issue_tracking-github-blue
         :target: https://github.com/diffpy/diffpy.morph/issues
 
-Python package for manipulating and comparing diffraction data
+Python package for manipulating and comparing diffraction data.
 
 ``diffpy.morph`` is a Python software package designed to increase the insight
 researchers can obtain from measured data including diffraction data
diff --git a/docs/source/index.rst b/docs/source/index.rst
index eb981226..59936edd 100644
--- a/docs/source/index.rst
+++ b/docs/source/index.rst
@@ -2,7 +2,7 @@
 diffpy.morph documentation
 ##########################
 
-``diffpy.morph`` - Tools for manipulating and comparing PDF profiles
+``diffpy.morph`` - Tools for manipulating and comparing 1D signals.
 
 | Software version |release|
 | Last updated |today|.
diff --git a/news/error-message.rst b/news/error-message.rst
new file mode 100644
index 00000000..aa3db216
--- /dev/null
+++ b/news/error-message.rst
@@ -0,0 +1,23 @@
+**Added:**
+
+* <news item>
+
+**Changed:**
+
+* Program no longer gives SystemExit. Proper errors are assigned to each case.
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>
diff --git a/news/save_pdf.rst b/news/save_pdf.rst
new file mode 100644
index 00000000..b01e6998
--- /dev/null
+++ b/news/save_pdf.rst
@@ -0,0 +1,23 @@
+**Added:**
+
+* <news item>
+
+**Changed:**
+
+* Default labels for saving are now [x] and [fx] instead of [r] and [gr].
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>
diff --git a/news/squeeze_tests.rst b/news/squeeze_tests.rst
new file mode 100644
index 00000000..7d73a2bf
--- /dev/null
+++ b/news/squeeze_tests.rst
@@ -0,0 +1,23 @@
+**Added:**
+
+* No news: fixing tests, no user-facing changes.
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>
diff --git a/src/diffpy/morph/__init__.py b/src/diffpy/morph/__init__.py
index 48455828..c2baddb1 100644
--- a/src/diffpy/morph/__init__.py
+++ b/src/diffpy/morph/__init__.py
@@ -12,7 +12,7 @@
 # See LICENSE.rst for license information.
 #
 ##############################################################################
-"""Python package for manipulating and comparing PDF profiles."""
+"""Python package for manipulating and comparing 1D signals."""
 
 # key used when saving multiple morphs
 __save_morph_as__ = "save_morph_as"
diff --git a/src/diffpy/morph/morph_io.py b/src/diffpy/morph/morph_io.py
index b0d80b68..cf194f54 100644
--- a/src/diffpy/morph/morph_io.py
+++ b/src/diffpy/morph/morph_io.py
@@ -223,7 +223,7 @@ def single_morph_output(
             path_name = "NO FILE PATH PROVIDED"
         else:
             path_name = str(Path(morph_file).resolve())
-        header = "# PDF created by diffpy.morph\n"
+        header = "# Function created by diffpy.morph\n"
         header += f"# from {path_name}"
 
         header_verbose = f"{morphs_in}\n{morphs_out}"
@@ -236,7 +236,7 @@ def single_morph_output(
                     print(header_verbose, file=outfile)
 
                 # Print table with label
-                print("\n# Labels: [r] [gr]", file=outfile)
+                print("\n# Labels: [x] [fx]", file=outfile)
                 numpy.savetxt(outfile, numpy.transpose(xy_out))
 
             if stdout_flag:
@@ -246,7 +246,7 @@ def single_morph_output(
 
         else:
             # Just print table with label if save is to stdout
-            print("# Labels: [r] [gr]")
+            print("# Labels: [x] [fx]")
             numpy.savetxt(sys.stdout, numpy.transpose(xy_out))
 
 
diff --git a/src/diffpy/morph/morphapp.py b/src/diffpy/morph/morphapp.py
index 22b6780a..5b03a6ad 100755
--- a/src/diffpy/morph/morphapp.py
+++ b/src/diffpy/morph/morphapp.py
@@ -41,13 +41,13 @@ class CustomParser(optparse.OptionParser):
         def __init__(self, *args, **kwargs):
             super(CustomParser, self).__init__(*args, **kwargs)
 
-        def custom_error(self, msg):
-            """custom_error(msg : string)
+        def morph_error(self, msg, error):
+            """morph_error(msg : string)
 
             Print a message incorporating 'msg' to stderr and exit. Does
             not print usage.
             """
-            self.exit(2, "%s: error: %s\n" % (self.get_prog_name(), msg))
+            raise error(f"{self.get_prog_name()}: {msg}")
 
     parser = CustomParser(
         usage="\n".join(
@@ -507,14 +507,17 @@ def single_morph(
     parser, opts, pargs, stdout_flag=True, python_wrap=False, pymorphs=None
 ):
     if len(pargs) < 2:
-        parser.error("You must supply MORPHFILE and TARGETFILE.")
+        parser.morph_error(
+            "You must supply MORPHFILE and TARGETFILE.", TypeError
+        )
     elif len(pargs) > 2 and not python_wrap:
-        parser.error(
+        parser.morph_error(
             "Too many arguments. Make sure you only supply "
-            "MORPHFILE and TARGETFILE."
+            "MORPHFILE and TARGETFILE.",
+            TypeError,
         )
     elif not (len(pargs) == 2 or len(pargs) == 6) and python_wrap:
-        parser.error("Python wrapper error.")
+        parser.morph_error("Python wrapper error.", RuntimeError)
 
     # Get the PDFs
     # If we get from python, we may wrap, which has input size 4
@@ -528,9 +531,9 @@ def single_morph(
         x_target, y_target = getPDFFromFile(pargs[1])
 
     if y_morph is None:
-        parser.error(f"No data table found in: {pargs[0]}.")
+        parser.morph_error(f"No data table found in: {pargs[0]}.", ValueError)
     if y_target is None:
-        parser.error(f"No data table found in: {pargs[1]}.")
+        parser.morph_error(f"No data table found in: {pargs[1]}.", ValueError)
 
     # Get tolerance
     tolerance = 1e-08
@@ -549,8 +552,8 @@ def single_morph(
         and opts.xmax is not None
         and opts.xmax <= opts.xmin
     ):
-        e = "xmin must be less than xmax"
-        parser.custom_error(e)
+        emsg = "xmin must be less than xmax"
+        parser.morph_error(emsg, ValueError)
 
     # Set up the morphs
     chain = morphs.MorphChain(config)
@@ -607,7 +610,9 @@ def single_morph(
                     squeeze_dict_in.update({f"a{idx}": float(coeff)})
                     idx += 1
                 except ValueError:
-                    parser.error(f"{coeff} could not be converted to float.")
+                    parser.morph_error(
+                        f"{coeff} could not be converted to float.", ValueError
+                    )
         squeeze_poly_deg = len(squeeze_dict_in.keys())
         squeeze_morph = morphs.MorphSqueeze()
         chain.append(squeeze_morph)
@@ -727,7 +732,7 @@ def single_morph(
             # Adjust all parameters
             refiner.refine(*refpars)
         except ValueError as e:
-            parser.custom_error(str(e))
+            parser.morph_error(str(e), ValueError)
     # Smear is not being refined, but baselineslope needs to refined to apply
     # smear
     # Note that baselineslope is only added to the refine list if smear is
@@ -738,7 +743,7 @@ def single_morph(
                 "baselineslope", baselineslope=config["baselineslope"]
             )
         except ValueError as e:
-            parser.custom_error(str(e))
+            parser.morph_error(str(e), ValueError)
     else:
         chain(x_morph, y_morph, x_target, y_target)
 
@@ -827,9 +832,9 @@ def single_morph(
             stdout_flag=stdout_flag,
         )
 
-    except (FileNotFoundError, RuntimeError):
+    except (FileNotFoundError, RuntimeError) as e:
         save_fail_message = "Unable to save to designated location."
-        parser.custom_error(save_fail_message)
+        parser.morph_error(save_fail_message, type(e))
 
     if opts.plot:
         pairlist = [chain.xy_target_out, chain.xy_morph_out]
@@ -871,25 +876,29 @@ def multiple_targets(parser, opts, pargs, stdout_flag=True, python_wrap=False):
     # Custom error messages since usage is distinct when --multiple tag is
     # applied
     if len(pargs) < 2:
-        parser.custom_error(
+        parser.morph_error(
             "You must supply a FILE and DIRECTORY. "
-            "See --multiple-targets under --help for usage."
+            "See --multiple-targets under --help for usage.",
+            TypeError,
         )
     elif len(pargs) > 2:
-        parser.custom_error(
-            "Too many arguments. You must only supply a FILE and a DIRECTORY."
+        parser.morph_error(
+            "Too many arguments. You must only supply a FILE and a DIRECTORY.",
+            TypeError,
         )
 
     # Parse paths
     morph_file = Path(pargs[0])
     if not morph_file.is_file():
-        parser.custom_error(
-            f"{morph_file} is not a file. Go to --help for usage."
+        parser.morph_error(
+            f"{morph_file} is not a file. Go to --help for usage.",
+            FileNotFoundError,
         )
     target_directory = Path(pargs[1])
     if not target_directory.is_dir():
-        parser.custom_error(
-            f"{target_directory} is not a directory. Go to --help for usage."
+        parser.morph_error(
+            f"{target_directory} is not a directory. Go to --help for usage.",
+            NotADirectoryError,
         )
 
     # Get list of files from target directory
@@ -926,12 +935,14 @@ def multiple_targets(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             )
         except KeyError:
             if opts.serfile is not None:
-                parser.custom_error(
-                    "The requested field was not found in the metadata file."
+                parser.morph_error(
+                    "The requested field was not found in the metadata file.",
+                    KeyError,
                 )
             else:
-                parser.custom_error(
-                    "The requested field is missing from a file header."
+                parser.morph_error(
+                    "The requested field is missing from a file header.",
+                    KeyError,
                 )
     else:
         # Default is alphabetical sort
@@ -953,9 +964,9 @@ def multiple_targets(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             save_morphs_here = io.create_morphs_directory(save_directory)
 
         # Could not create directory or find names to save morphs as
-        except (FileNotFoundError, RuntimeError):
+        except (FileNotFoundError, RuntimeError) as e:
             save_fail_message = "\nUnable to create directory"
-            parser.custom_error(save_fail_message)
+            parser.morph_error(save_fail_message, type(e))
 
         try:
             save_names = io.get_multisave_names(
@@ -964,7 +975,7 @@ def multiple_targets(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             # Could not create directory or find names to save morphs as
         except FileNotFoundError:
             save_fail_message = "\nUnable to read from save names file"
-            parser.custom_error(save_fail_message)
+            parser.morph_error(save_fail_message, FileNotFoundError)
 
     # Morph morph_file against all other files in target_directory
     morph_results = {}
@@ -1013,9 +1024,9 @@ def multiple_targets(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             verbose=opts.verbose,
             stdout_flag=stdout_flag,
         )
-    except (FileNotFoundError, RuntimeError):
+    except (FileNotFoundError, RuntimeError) as e:
         save_fail_message = "Unable to save summary to directory."
-        parser.custom_error(save_fail_message)
+        parser.morph_error(save_fail_message, type(e))
 
     # Plot the values of some parameter for each target if requested
     if plot_opt:
@@ -1032,8 +1043,9 @@ def multiple_targets(parser, opts, pargs, stdout_flag=True, python_wrap=False):
         # Not an available parameter to plot or no values found for the
         # parameter
         if param_list is None:
-            parser.custom_error(
-                "Cannot find specified plot parameter. No plot shown."
+            parser.morph_error(
+                "Cannot find specified plot parameter. No plot shown.",
+                KeyError,
             )
         else:
             try:
@@ -1045,9 +1057,10 @@ def multiple_targets(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             # i.e. --smear is not selected as an option, but smear is the
             # plotting parameter
             except ValueError:
-                parser.custom_error(
+                parser.morph_error(
                     "The plot parameter is missing values for at least one "
-                    "morph and target pair. No plot shown."
+                    "morph and target pair. No plot shown.",
+                    ValueError,
                 )
 
     return morph_results
@@ -1057,25 +1070,29 @@ def multiple_morphs(parser, opts, pargs, stdout_flag=True, python_wrap=False):
     # Custom error messages since usage is distinct when --multiple tag is
     # applied
     if len(pargs) < 2:
-        parser.custom_error(
+        parser.morph_error(
             "You must supply a DIRECTORY and FILE. "
-            "See --multiple-morphs under --help for usage."
+            "See --multiple-morphs under --help for usage.",
+            TypeError,
         )
     elif len(pargs) > 2:
-        parser.custom_error(
-            "Too many arguments. You must only supply a DIRECTORY and FILE."
+        parser.morph_error(
+            "Too many arguments. You must only supply a DIRECTORY and FILE.",
+            TypeError,
         )
 
     # Parse paths
     target_file = Path(pargs[1])
     if not target_file.is_file():
-        parser.custom_error(
-            f"{target_file} is not a file. Go to --help for usage."
+        parser.morph_error(
+            f"{target_file} is not a file. Go to --help for usage.",
+            FileNotFoundError,
         )
     morph_directory = Path(pargs[0])
     if not morph_directory.is_dir():
-        parser.custom_error(
-            f"{morph_directory} is not a directory. Go to --help for usage."
+        parser.morph_error(
+            f"{morph_directory} is not a directory. Go to --help for usage.",
+            NotADirectoryError,
         )
 
     # Get list of files from morph directory
@@ -1112,12 +1129,14 @@ def multiple_morphs(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             )
         except KeyError:
             if opts.serfile is not None:
-                parser.custom_error(
-                    "The requested field was not found in the metadata file."
+                parser.morph_error(
+                    "The requested field was not found in the metadata file.",
+                    KeyError,
                 )
             else:
-                parser.custom_error(
-                    "The requested field is missing from a PDF file header."
+                parser.morph_error(
+                    "The requested field is missing from a PDF file header.",
+                    KeyError,
                 )
     else:
         # Default is alphabetical sort
@@ -1139,9 +1158,9 @@ def multiple_morphs(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             save_morphs_here = io.create_morphs_directory(save_directory)
 
         # Could not create directory or find names to save morphs as
-        except (FileNotFoundError, RuntimeError):
+        except (FileNotFoundError, RuntimeError) as e:
             save_fail_message = "\nUnable to create directory"
-            parser.custom_error(save_fail_message)
+            parser.morph_error(save_fail_message, type(e))
 
         try:
             save_names = io.get_multisave_names(
@@ -1150,7 +1169,7 @@ def multiple_morphs(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             # Could not create directory or find names to save morphs as
         except FileNotFoundError:
             save_fail_message = "\nUnable to read from save names file"
-            parser.custom_error(save_fail_message)
+            parser.morph_error(save_fail_message, FileNotFoundError)
 
     # Morph morph_file against all other files in target_directory
     morph_results = {}
@@ -1200,9 +1219,9 @@ def multiple_morphs(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             stdout_flag=stdout_flag,
             mm=True,
         )
-    except (FileNotFoundError, RuntimeError):
+    except (FileNotFoundError, RuntimeError) as e:
         save_fail_message = "Unable to save summary to directory."
-        parser.custom_error(save_fail_message)
+        parser.morph_error(save_fail_message, type(e))
 
     # Plot the values of some parameter for each target if requested
     if plot_opt:
@@ -1219,8 +1238,9 @@ def multiple_morphs(parser, opts, pargs, stdout_flag=True, python_wrap=False):
         # Not an available parameter to plot or no values found for the
         # parameter
         if param_list is None:
-            parser.custom_error(
-                "Cannot find specified plot parameter. No plot shown."
+            parser.morph_error(
+                "Cannot find specified plot parameter. No plot shown.",
+                KeyError,
             )
         else:
             try:
@@ -1232,9 +1252,10 @@ def multiple_morphs(parser, opts, pargs, stdout_flag=True, python_wrap=False):
             # i.e. --smear is not selected as an option, but smear is the
             # plotting parameter
             except ValueError:
-                parser.custom_error(
+                parser.morph_error(
                     "The plot parameter is missing values for at least one "
-                    "morph and target pair. No plot shown."
+                    "morph and target pair. No plot shown.",
+                    ValueError,
                 )
 
     return morph_results
diff --git a/tests/test_morphapp.py b/tests/test_morphapp.py
index b4729d4d..a414e932 100644
--- a/tests/test_morphapp.py
+++ b/tests/test_morphapp.py
@@ -105,43 +105,40 @@ def test_parser_numerical(self, setup_parser):
             )  # Check correct value parsed
         assert len(n_args) == 1  # Check one leftover
 
-    def test_parser_systemexits(self, capsys, setup_parser):
+    def test_parser_errors(self, capsys, setup_parser):
         # ###Basic tests for any variety of morphing###
 
         # Ensure only two pargs given for morphing
         (opts, pargs) = self.parser.parse_args(["toofewfiles"])
-        with pytest.raises(SystemExit):
+        with pytest.raises(TypeError) as excinfo:
             single_morph(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "You must supply MORPHFILE and TARGETFILE." in err
-        with pytest.raises(SystemExit):
+        assert "You must supply MORPHFILE and TARGETFILE." in str(
+            excinfo.value
+        )
+        with pytest.raises(TypeError) as excinfo:
             multiple_targets(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "You must supply a FILE and DIRECTORY." in err
+        assert "You must supply a FILE and DIRECTORY." in str(excinfo.value)
         (opts, pargs) = self.parser.parse_args(["too", "many", "files"])
-        with pytest.raises(SystemExit):
+        with pytest.raises(TypeError) as excinfo:
             single_morph(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
         assert (
             "Too many arguments. Make sure you only supply MORPHFILE and "
-            "TARGETFILE." in err
+            "TARGETFILE." in str(excinfo.value)
         )
-        with pytest.raises(SystemExit):
+        with pytest.raises(TypeError) as excinfo:
             multiple_targets(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
         assert (
             "Too many arguments. You must only supply a FILE and a DIRECTORY."
-            in err
+            in str(excinfo.value)
         )
 
         # Make sure xmax greater than xmin
         (opts, pargs) = self.parser.parse_args(
             [f"{nickel_PDF}", f"{nickel_PDF}", "--xmin", "10", "--xmax", "1"]
         )
-        with pytest.raises(SystemExit):
+        with pytest.raises(ValueError) as excinfo:
             single_morph(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "xmin must be less than xmax" in err
+        assert "xmin must be less than xmax" in str(excinfo.value)
 
         # ###Tests exclusive to multiple morphs###
         # Make sure we save to a directory that exists
@@ -154,39 +151,36 @@ def test_parser_systemexits(self, capsys, setup_parser):
                 "/nonexisting_directory/no_way_this_exists/nonexisting_path",
             ]
         )
-        with pytest.raises(SystemExit):
+        with pytest.raises(FileNotFoundError) as excinfo:
             single_morph(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "Unable to save to designated location." in err
-        with pytest.raises(SystemExit):
+        assert "Unable to save to designated location." in str(excinfo.value)
+        with pytest.raises(NotADirectoryError) as excinfo:
             multiple_targets(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "is not a directory." in err
+        assert "is not a directory." in str(excinfo.value)
 
         # Ensure first parg is a FILE and second parg is a DIRECTORY
         (opts, pargs) = self.parser.parse_args(
             [f"{nickel_PDF}", f"{nickel_PDF}"]
         )
-        with pytest.raises(SystemExit):
+        with pytest.raises(NotADirectoryError) as excinfo:
             multiple_targets(self.parser, opts, pargs, stdout_flag=False)
         (opts, pargs) = self.parser.parse_args(
             [f"{testsequence_dir}", f"{testsequence_dir}"]
         )
-        _, err = capsys.readouterr()
-        assert "is not a directory." in err
-        with pytest.raises(SystemExit):
+        assert "is not a directory." in str(excinfo.value)
+        with pytest.raises(FileNotFoundError) as excinfo:
             multiple_targets(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "is not a file." in err
+        assert "is not a file." in str(excinfo.value)
 
         # Try sorting by non-existing field
         (opts, pargs) = self.parser.parse_args(
             [f"{nickel_PDF}", f"{testsequence_dir}", "--sort-by", "fake_field"]
         )
-        with pytest.raises(SystemExit):
+        with pytest.raises(KeyError) as excinfo:
             multiple_targets(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "The requested field is missing from a file header." in err
+        assert "The requested field is missing from a file header." in str(
+            excinfo.value
+        )
         (opts, pargs) = self.parser.parse_args(
             [
                 f"{nickel_PDF}",
@@ -197,10 +191,12 @@ def test_parser_systemexits(self, capsys, setup_parser):
                 f"{serial_JSON}",
             ]
         )
-        with pytest.raises(SystemExit):
+        with pytest.raises(KeyError) as excinfo:
             multiple_targets(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "The requested field was not found in the metadata file." in err
+        assert (
+            "The requested field was not found in the metadata file."
+            in str(excinfo.value)
+        )
 
         # Try plotting an unknown parameter
         (opts, pargs) = self.parser.parse_args(
@@ -211,10 +207,11 @@ def test_parser_systemexits(self, capsys, setup_parser):
                 "unknown",
             ]
         )
-        with pytest.raises(SystemExit):
+        with pytest.raises(KeyError) as excinfo:
             multiple_targets(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "Cannot find specified plot parameter. No plot shown." in err
+        assert "Cannot find specified plot parameter. No plot shown." in str(
+            excinfo.value
+        )
 
         # Try plotting an unrefined parameter
         (opts, pargs) = self.parser.parse_args(
@@ -225,13 +222,12 @@ def test_parser_systemexits(self, capsys, setup_parser):
                 "stretch",
             ]
         )
-        with pytest.raises(SystemExit):
+        with pytest.raises(ValueError) as excinfo:
             multiple_targets(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
         assert (
             "The plot parameter is missing values for at "
             "least one morph and target pair. "
-            "No plot shown." in err
+            "No plot shown." in str(excinfo.value)
         )
 
         # Pass a non-float list to squeeze
@@ -243,10 +239,9 @@ def test_parser_systemexits(self, capsys, setup_parser):
                 "1,a,0",
             ]
         )
-        with pytest.raises(SystemExit):
+        with pytest.raises(ValueError) as excinfo:
             single_morph(self.parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert "a could not be converted to float." in err
+        assert "a could not be converted to float." in str(excinfo.value)
 
     def test_morphsequence(self, setup_morphsequence):
         # Parse arguments sorting by field
diff --git a/tests/test_morphsqueeze.py b/tests/test_morphsqueeze.py
index 8a172086..90de2a6c 100644
--- a/tests/test_morphsqueeze.py
+++ b/tests/test_morphsqueeze.py
@@ -148,11 +148,16 @@ def test_morphsqueeze_extrapolate(user_filesystem, squeeze_coeffs, wmsg_gen):
             squeeze=coeffs,
             apply=True,
         )
-        assert len(warning) == 1
-        assert warning[0].category is UserWarning
-        actual_wmsg = str(warning[0].message)
-    expected_wmsg = wmsg_gen([min(x_squeezed), max(x_squeezed)])
-    assert actual_wmsg == expected_wmsg
+        assert len(warning) >= 1
+        expected_wmsg = wmsg_gen([min(x_squeezed), max(x_squeezed)])
+        message_found = False
+        for w in warning:
+            actual_wmsg = str(w.message)
+            if actual_wmsg == expected_wmsg:
+                if w.category is UserWarning:
+                    message_found = True
+                    break
+        assert message_found
 
     # CLI test
     morph_file, target_file = create_morph_data_file(
@@ -272,9 +277,7 @@ def test_squeeze_warnings(user_filesystem, squeeze_coeffs, x_morph):
             squeeze=squeeze_coeffs,
             apply=True,
         )
-    assert len(warning) == 1
-    assert warning[0].category is UserWarning
-    actual_wmsg = str(warning[0].message)
+    assert len(warning) >= 1
     expected_wmsg = (
         "Warning: The squeeze morph has interpolated your morphed "
         "function from a non-monotonically increasing grid. "
@@ -295,7 +298,14 @@ def test_squeeze_warnings(user_filesystem, squeeze_coeffs, x_morph):
         "first apply a --hshift and --stretch morph. "
         "Then, use the hshift parameter for a0 and stretch parameter for a1."
     )
-    assert expected_wmsg in actual_wmsg
+    message_found = False
+    for w in warning:
+        actual_wmsg = str(w.message)
+        if expected_wmsg in actual_wmsg:
+            if w.category is UserWarning:
+                message_found = True
+                break
+    assert message_found
 
     # call in CLI
     morph_file, target_file = create_morph_data_file(
@@ -314,9 +324,13 @@ def test_squeeze_warnings(user_filesystem, squeeze_coeffs, x_morph):
     )
     with pytest.warns(UserWarning) as warning:
         single_morph(parser, opts, pargs, stdout_flag=False)
-    assert len(warning) == 1
-    actual_wmsg = str(warning[0].message)
-    assert expected_wmsg in actual_wmsg
+    assert len(warning) >= 1
+    message_found = False
+    for w in warning:
+        actual_wmsg = str(w.message)
+        if expected_wmsg in actual_wmsg:
+            message_found = True
+    assert message_found
 
 
 @pytest.mark.parametrize(
diff --git a/tests/test_refine.py b/tests/test_refine.py
index b64bccd1..fe9e9937 100644
--- a/tests/test_refine.py
+++ b/tests/test_refine.py
@@ -231,10 +231,9 @@ def test_refine_grid_bad(self, user_filesystem, capsys):
         run_cmd.append("-n")
         parser = create_option_parser()
         (opts, pargs) = parser.parse_args(run_cmd)
-        with pytest.raises(SystemExit):
+        with pytest.raises(ValueError) as excinfo:
             single_morph(parser, opts, pargs, stdout_flag=False)
-        _, err = capsys.readouterr()
-        assert expected_error_message in actual_error_message
+        assert expected_error_message in str(excinfo.value)
 
 
 # End of class TestRefine
diff --git a/tests/testdata/funcy_target.cgr b/tests/testdata/funcy_target.cgr
index fa36dc6b..108fde4d 100644
--- a/tests/testdata/funcy_target.cgr
+++ b/tests/testdata/funcy_target.cgr
@@ -1,4 +1,4 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from NO FILE PATH PROVIDED
 
 # Input morphing parameters:
@@ -32,7 +32,7 @@ def quadratic(x, y, a0, a1, a2):
 # Rw = 0.000000
 # Pearson = 1.000000
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 1.000000000000000000e+00
 1.000000000000000056e-01 1.229999999999999982e+00
 2.000000000000000111e-01 1.520000000000000018e+00
diff --git a/tests/testdata/squeeze_morph.cgr b/tests/testdata/squeeze_morph.cgr
index cc7799b9..ee388096 100644
--- a/tests/testdata/squeeze_morph.cgr
+++ b/tests/testdata/squeeze_morph.cgr
@@ -1,7 +1,7 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000056e-01 2.016607210740701817e-01
 2.000000000000000111e-01 4.012816425967311584e-01
diff --git a/tests/testdata/squeeze_target.cgr b/tests/testdata/squeeze_target.cgr
index 1474409a..e5ab4504 100644
--- a/tests/testdata/squeeze_target.cgr
+++ b/tests/testdata/squeeze_target.cgr
@@ -1,4 +1,4 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
 # Input morphing parameters:
@@ -24,7 +24,7 @@
 # Rw = 0.000000
 # Pearson = 1.000000
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 -8.357788796904224253e-08
 1.000000000000000056e-01 9.983335989539958433e-02
 2.000000000000000111e-01 1.986692882755068390e-01
diff --git a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_a.cgr b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_a.cgr
index c1b2cb4c..041f42fa 100644
--- a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_a.cgr
+++ b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_a.cgr
@@ -1,7 +1,7 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_b.cgr b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_b.cgr
index c1b2cb4c..041f42fa 100644
--- a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_b.cgr
+++ b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_b.cgr
@@ -1,7 +1,7 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_c.cgr b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_c.cgr
index c1b2cb4c..041f42fa 100644
--- a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_c.cgr
+++ b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_c.cgr
@@ -1,7 +1,7 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_d.cgr b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_d.cgr
index c1b2cb4c..041f42fa 100644
--- a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_d.cgr
+++ b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_d.cgr
@@ -1,7 +1,7 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_e.cgr b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_e.cgr
index c1b2cb4c..041f42fa 100644
--- a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_e.cgr
+++ b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_e.cgr
@@ -1,7 +1,7 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_f.cgr b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_f.cgr
index c1b2cb4c..041f42fa 100644
--- a/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_f.cgr
+++ b/tests/testdata/testsequence/testsaving/succinct/Morphs/mwt_f.cgr
@@ -1,7 +1,7 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/succinct/single_succinct_morph.cgr b/tests/testdata/testsequence/testsaving/succinct/single_succinct_morph.cgr
index c1b2cb4c..041f42fa 100644
--- a/tests/testdata/testsequence/testsaving/succinct/single_succinct_morph.cgr
+++ b/tests/testdata/testsequence/testsaving/succinct/single_succinct_morph.cgr
@@ -1,7 +1,7 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_a.cgr b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_a.cgr
index 95cba1f9..eed0c27f 100644
--- a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_a.cgr
+++ b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_a.cgr
@@ -1,4 +1,4 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
 # Input morphing parameters:
@@ -15,7 +15,7 @@
 # Rw = 0.127100
 # Pearson = 0.992111
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_b.cgr b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_b.cgr
index ef8cf023..a41aa616 100644
--- a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_b.cgr
+++ b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_b.cgr
@@ -1,4 +1,4 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
 # Input morphing parameters:
@@ -15,7 +15,7 @@
 # Rw = 0.117595
 # Pearson = 0.993160
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_c.cgr b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_c.cgr
index 27ebcd00..c53e08c6 100644
--- a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_c.cgr
+++ b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_c.cgr
@@ -1,4 +1,4 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
 # Input morphing parameters:
@@ -15,7 +15,7 @@
 # Rw = 0.105918
 # Pearson = 0.994409
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_d.cgr b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_d.cgr
index 8a30b321..d77b671d 100644
--- a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_d.cgr
+++ b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_d.cgr
@@ -1,4 +1,4 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
 # Input morphing parameters:
@@ -15,7 +15,7 @@
 # Rw = 0.062392
 # Pearson = 0.998077
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_e.cgr b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_e.cgr
index 1ad1a45f..b4d00115 100644
--- a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_e.cgr
+++ b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_e.cgr
@@ -1,4 +1,4 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
 # Input morphing parameters:
@@ -15,7 +15,7 @@
 # Rw = 0.034859
 # Pearson = 0.999424
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_f.cgr b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_f.cgr
index 32ce202b..8e8aa722 100644
--- a/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_f.cgr
+++ b/tests/testdata/testsequence/testsaving/verbose/Morphs/mwt_f.cgr
@@ -1,4 +1,4 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
 # Input morphing parameters:
@@ -15,7 +15,7 @@
 # Rw = 0.020141
 # Pearson = 0.999810
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04
diff --git a/tests/testdata/testsequence/testsaving/verbose/single_verbose_morph.cgr b/tests/testdata/testsequence/testsaving/verbose/single_verbose_morph.cgr
index 95cba1f9..eed0c27f 100644
--- a/tests/testdata/testsequence/testsaving/verbose/single_verbose_morph.cgr
+++ b/tests/testdata/testsequence/testsaving/verbose/single_verbose_morph.cgr
@@ -1,4 +1,4 @@
-# PDF created by diffpy.morph
+# Function created by diffpy.morph
 # from PATH
 
 # Input morphing parameters:
@@ -15,7 +15,7 @@
 # Rw = 0.127100
 # Pearson = 0.992111
 
-# Labels: [r] [gr]
+# Labels: [x] [fx]
 0.000000000000000000e+00 0.000000000000000000e+00
 1.000000000000000021e-02 4.042510000000000027e-04
 2.000000000000000042e-02 7.817419999999999838e-04