diff --git a/check/checkfunctions/checkfunctions.go b/check/checkfunctions/checkfunctions.go
index ef64a7fb1..dc1e282ff 100644
--- a/check/checkfunctions/checkfunctions.go
+++ b/check/checkfunctions/checkfunctions.go
@@ -72,7 +72,7 @@ func containsIncorrectPathBaseCase(pathList paths.PathList, correctBaseName stri
 // MissingReadme checks if the project has a readme that will be recognized by GitHub.
 func MissingReadme() (result checkresult.Type, output string) {
 	if checkdata.ProjectType() != checkdata.SuperProjectType() {
-		return checkresult.NotRun, "Readme not required for subprojects"
+		return checkresult.Skip, "Readme not required for subprojects"
 	}
 
 	// https://github.com/github/markup/blob/master/README.md
@@ -91,7 +91,7 @@ func MissingReadme() (result checkresult.Type, output string) {
 // MissingLicenseFile checks if the project has a license file that will be recognized by GitHub.
 func MissingLicenseFile() (result checkresult.Type, output string) {
 	if checkdata.ProjectType() != checkdata.SuperProjectType() {
-		return checkresult.NotRun, "License file not required for subprojects"
+		return checkresult.Skip, "License file not required for subprojects"
 	}
 
 	// https://docs.github.com/en/free-pro-team@latest/github/creating-cloning-and-archiving-repositories/licensing-a-repository#detecting-a-license
diff --git a/check/checkfunctions/checkfunctions_test.go b/check/checkfunctions/checkfunctions_test.go
index c85adb849..7c5b42f89 100644
--- a/check/checkfunctions/checkfunctions_test.go
+++ b/check/checkfunctions/checkfunctions_test.go
@@ -64,7 +64,7 @@ func checkCheckFunction(checkFunction Type, testTables []checkFunctionTestTable,
 
 func TestMissingReadme(t *testing.T) {
 	testTables := []checkFunctionTestTable{
-		{"Subproject", "readme", projecttype.Sketch, projecttype.Library, checkresult.NotRun, ""},
+		{"Subproject", "readme", projecttype.Sketch, projecttype.Library, checkresult.Skip, ""},
 		{"Readme", "readme", projecttype.Sketch, projecttype.Sketch, checkresult.Pass, ""},
 		{"No readme", "no-readme", projecttype.Sketch, projecttype.Sketch, checkresult.Fail, ""},
 	}
@@ -74,7 +74,7 @@ func TestMissingReadme(t *testing.T) {
 
 func TestMissingLicenseFile(t *testing.T) {
 	testTables := []checkFunctionTestTable{
-		{"Subproject", "no-license-file", projecttype.Sketch, projecttype.Library, checkresult.NotRun, ""},
+		{"Subproject", "no-license-file", projecttype.Sketch, projecttype.Library, checkresult.Skip, ""},
 		{"Has license", "license-file", projecttype.Sketch, projecttype.Sketch, checkresult.Pass, ""},
 		{"Has license in subfolder", "license-file-in-subfolder", projecttype.Sketch, projecttype.Sketch, checkresult.Fail, ""},
 		{"No license", "no-license-file", projecttype.Sketch, projecttype.Sketch, checkresult.Fail, ""},
diff --git a/check/checkfunctions/library.go b/check/checkfunctions/library.go
index 1dbc0dce5..6f551911f 100644
--- a/check/checkfunctions/library.go
+++ b/check/checkfunctions/library.go
@@ -43,7 +43,7 @@ import (
 // LibraryPropertiesFormat checks for invalid library.properties format.
 func LibraryPropertiesFormat() (result checkresult.Type, output string) {
 	if checkdata.LoadedLibrary() != nil && checkdata.LoadedLibrary().IsLegacy {
-		return checkresult.NotRun, "Library has no library.properties"
+		return checkresult.Skip, "Library has no library.properties"
 	}
 
 	if checkdata.LibraryPropertiesLoadError() != nil {
@@ -110,9 +110,12 @@ func RedundantLibraryProperties() (result checkresult.Type, output string) {
 
 // LibraryPropertiesNameFieldMissing checks for missing library.properties "name" field.
 func LibraryPropertiesNameFieldMissing() (result checkresult.Type, output string) {
-	shouldRun, reason := runRequiredLibraryPropertiesFieldCheck()
-	if !shouldRun {
-		return checkresult.NotRun, reason
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, "Couldn't load library.properties"
+	}
+
+	if checkdata.LoadedLibrary().IsLegacy {
+		return checkresult.Skip, "Library has legacy format"
 	}
 
 	if schema.RequiredPropertyMissing("name", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -340,9 +343,12 @@ func LibraryPropertiesNameFieldHeaderMismatch() (result checkresult.Type, output
 
 // LibraryPropertiesVersionFieldMissing checks for missing library.properties "version" field.
 func LibraryPropertiesVersionFieldMissing() (result checkresult.Type, output string) {
-	shouldRun, reason := runRequiredLibraryPropertiesFieldCheck()
-	if !shouldRun {
-		return checkresult.NotRun, reason
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, "Couldn't load library.properties"
+	}
+
+	if checkdata.LoadedLibrary().IsLegacy {
+		return checkresult.Skip, "Library has legacy format"
 	}
 
 	if schema.RequiredPropertyMissing("version", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -390,7 +396,7 @@ func LibraryPropertiesVersionFieldNonSemver() (result checkresult.Type, output s
 // LibraryPropertiesVersionFieldBehindTag checks whether a release tag was made without first bumping the library.properties version value.
 func LibraryPropertiesVersionFieldBehindTag() (result checkresult.Type, output string) {
 	if checkdata.ProjectType() != checkdata.SuperProjectType() {
-		return checkresult.NotRun, "Not relevant for subprojects"
+		return checkresult.Skip, "Not relevant for subprojects"
 	}
 
 	if checkdata.LibraryPropertiesLoadError() != nil {
@@ -410,7 +416,7 @@ func LibraryPropertiesVersionFieldBehindTag() (result checkresult.Type, output s
 
 	repository, err := git.PlainOpen(checkdata.ProjectPath().String())
 	if err != nil {
-		return checkresult.NotRun, "Project path is not a repository"
+		return checkresult.Skip, "Project path is not a repository"
 	}
 
 	headRef, err := repository.Head()
@@ -482,9 +488,12 @@ func LibraryPropertiesVersionFieldBehindTag() (result checkresult.Type, output s
 
 // LibraryPropertiesAuthorFieldMissing checks for missing library.properties "author" field.
 func LibraryPropertiesAuthorFieldMissing() (result checkresult.Type, output string) {
-	shouldRun, reason := runRequiredLibraryPropertiesFieldCheck()
-	if !shouldRun {
-		return checkresult.NotRun, reason
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, "Couldn't load library.properties"
+	}
+
+	if checkdata.LoadedLibrary().IsLegacy {
+		return checkresult.Skip, "Library has legacy format"
 	}
 
 	if schema.RequiredPropertyMissing("author", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -512,9 +521,12 @@ func LibraryPropertiesAuthorFieldLTMinLength() (result checkresult.Type, output
 
 // LibraryPropertiesMaintainerFieldMissing checks for missing library.properties "maintainer" field.
 func LibraryPropertiesMaintainerFieldMissing() (result checkresult.Type, output string) {
-	shouldRun, reason := runRequiredLibraryPropertiesFieldCheck()
-	if !shouldRun {
-		return checkresult.NotRun, reason
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, "Couldn't load library.properties"
+	}
+
+	if checkdata.LoadedLibrary().IsLegacy {
+		return checkresult.Skip, "Library has legacy format"
 	}
 
 	if schema.RequiredPropertyMissing("maintainer", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -565,7 +577,7 @@ func LibraryPropertiesEmailFieldAsMaintainerAlias() (result checkresult.Type, ou
 	}
 
 	if !checkdata.LibraryProperties().ContainsKey("email") {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if !checkdata.LibraryProperties().ContainsKey("maintainer") {
@@ -582,7 +594,7 @@ func LibraryPropertiesEmailFieldLTMinLength() (result checkresult.Type, output s
 	}
 
 	if checkdata.LibraryProperties().ContainsKey("maintainer") || !checkdata.LibraryProperties().ContainsKey("email") {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if schema.PropertyLessThanMinLength("email", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -604,7 +616,7 @@ func LibraryPropertiesEmailFieldStartsWithArduino() (result checkresult.Type, ou
 
 	email, ok := checkdata.LibraryProperties().GetOk("email")
 	if !ok {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if schema.ValidationErrorMatch("^#/email$", "/patternObjects/notStartsWithArduino", "", "", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -616,9 +628,12 @@ func LibraryPropertiesEmailFieldStartsWithArduino() (result checkresult.Type, ou
 
 // LibraryPropertiesSentenceFieldMissing checks for missing library.properties "sentence" field.
 func LibraryPropertiesSentenceFieldMissing() (result checkresult.Type, output string) {
-	shouldRun, reason := runRequiredLibraryPropertiesFieldCheck()
-	if !shouldRun {
-		return checkresult.NotRun, reason
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, "Couldn't load library.properties"
+	}
+
+	if checkdata.LoadedLibrary().IsLegacy {
+		return checkresult.Skip, "Library has legacy format"
 	}
 
 	if schema.RequiredPropertyMissing("sentence", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -651,9 +666,12 @@ func LibraryPropertiesSentenceFieldSpellCheck() (result checkresult.Type, output
 
 // LibraryPropertiesParagraphFieldMissing checks for missing library.properties "paragraph" field.
 func LibraryPropertiesParagraphFieldMissing() (result checkresult.Type, output string) {
-	shouldRun, reason := runRequiredLibraryPropertiesFieldCheck()
-	if !shouldRun {
-		return checkresult.NotRun, reason
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, "Couldn't load library.properties"
+	}
+
+	if checkdata.LoadedLibrary().IsLegacy {
+		return checkresult.Skip, "Library has legacy format"
 	}
 
 	if schema.RequiredPropertyMissing("paragraph", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -688,9 +706,12 @@ func LibraryPropertiesParagraphFieldRepeatsSentence() (result checkresult.Type,
 
 // LibraryPropertiesCategoryFieldMissing checks for missing library.properties "category" field.
 func LibraryPropertiesCategoryFieldMissing() (result checkresult.Type, output string) {
-	shouldRun, reason := runRequiredLibraryPropertiesFieldCheck()
-	if !shouldRun {
-		return checkresult.NotRun, reason
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, "Couldn't load library.properties"
+	}
+
+	if checkdata.LoadedLibrary().IsLegacy {
+		return checkresult.Skip, "Library has legacy format"
 	}
 
 	if schema.RequiredPropertyMissing("category", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -707,7 +728,7 @@ func LibraryPropertiesCategoryFieldInvalid() (result checkresult.Type, output st
 
 	category, ok := checkdata.LibraryProperties().GetOk("category")
 	if !ok {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if schema.PropertyEnumMismatch("category", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -725,7 +746,7 @@ func LibraryPropertiesCategoryFieldUncategorized() (result checkresult.Type, out
 
 	category, ok := checkdata.LibraryProperties().GetOk("category")
 	if !ok {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if category == "Uncategorized" {
@@ -737,9 +758,12 @@ func LibraryPropertiesCategoryFieldUncategorized() (result checkresult.Type, out
 
 // LibraryPropertiesUrlFieldMissing checks for missing library.properties "url" field.
 func LibraryPropertiesUrlFieldMissing() (result checkresult.Type, output string) {
-	shouldRun, reason := runRequiredLibraryPropertiesFieldCheck()
-	if !shouldRun {
-		return checkresult.NotRun, reason
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, "Couldn't load library.properties"
+	}
+
+	if checkdata.LoadedLibrary().IsLegacy {
+		return checkresult.Skip, "Library has legacy format"
 	}
 
 	if schema.RequiredPropertyMissing("url", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -792,9 +816,12 @@ func LibraryPropertiesUrlFieldDeadLink() (result checkresult.Type, output string
 
 // LibraryPropertiesArchitecturesFieldMissing checks for missing library.properties "architectures" field.
 func LibraryPropertiesArchitecturesFieldMissing() (result checkresult.Type, output string) {
-	shouldRun, reason := runRequiredLibraryPropertiesFieldCheck()
-	if !shouldRun {
-		return checkresult.NotRun, reason
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, "Couldn't load library.properties"
+	}
+
+	if checkdata.LoadedLibrary().IsLegacy {
+		return checkresult.Skip, "Library has legacy format"
 	}
 
 	if schema.RequiredPropertyMissing("architectures", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -810,7 +837,7 @@ func LibraryPropertiesArchitecturesFieldLTMinLength() (result checkresult.Type,
 	}
 
 	if !checkdata.LibraryProperties().ContainsKey("architectures") {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if schema.PropertyLessThanMinLength("architectures", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -828,7 +855,7 @@ func LibraryPropertiesDependsFieldDisallowedCharacters() (result checkresult.Typ
 
 	depends, ok := checkdata.LibraryProperties().GetOk("depends")
 	if !ok {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if schema.PropertyPatternMismatch("depends", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -846,7 +873,7 @@ func LibraryPropertiesDependsFieldNotInIndex() (result checkresult.Type, output
 
 	depends, hasDepends := checkdata.LibraryProperties().GetOk("depends")
 	if !hasDepends {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	dependencies := strings.Split(depends, ",")
@@ -878,7 +905,7 @@ func LibraryPropertiesDotALinkageFieldInvalid() (result checkresult.Type, output
 
 	dotALinkage, ok := checkdata.LibraryProperties().GetOk("dot_a_linkage")
 	if !ok {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if schema.PropertyEnumMismatch("dot_a_linkage", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -895,7 +922,7 @@ func LibraryPropertiesDotALinkageFieldTrueWithFlatLayout() (result checkresult.T
 	}
 
 	if !checkdata.LibraryProperties().ContainsKey("dot_a_linkage") {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if checkdata.LoadedLibrary().DotALinkage && checkdata.LoadedLibrary().Layout == libraries.FlatLayout {
@@ -912,7 +939,7 @@ func LibraryPropertiesIncludesFieldLTMinLength() (result checkresult.Type, outpu
 	}
 
 	if !checkdata.LibraryProperties().ContainsKey("includes") {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if schema.PropertyLessThanMinLength("includes", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -930,7 +957,7 @@ func LibraryPropertiesIncludesFieldItemNotFound() (result checkresult.Type, outp
 
 	includes, ok := checkdata.LibraryProperties().GetOk("includes")
 	if !ok {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	includesList := strings.Split(includes, ",")
@@ -972,7 +999,7 @@ func LibraryPropertiesPrecompiledFieldInvalid() (result checkresult.Type, output
 
 	precompiled, ok := checkdata.LibraryProperties().GetOk("precompiled")
 	if !ok {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if schema.PropertyEnumMismatch("precompiled", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
@@ -990,7 +1017,7 @@ func LibraryPropertiesPrecompiledFieldEnabledWithFlatLayout() (result checkresul
 
 	precompiled, ok := checkdata.LibraryProperties().GetOk("precompiled")
 	if !ok {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	if checkdata.LoadedLibrary().Precompiled && checkdata.LoadedLibrary().Layout == libraries.FlatLayout {
@@ -1006,6 +1033,10 @@ func LibraryPropertiesLdflagsFieldLTMinLength() (result checkresult.Type, output
 		return checkresult.NotRun, "Library not loaded"
 	}
 
+	if !checkdata.LibraryProperties().ContainsKey("ldflags") {
+		return checkresult.Skip, "Field not present"
+	}
+
 	if schema.PropertyLessThanMinLength("ldflags", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
 		return checkresult.Fail, ""
 	}
@@ -1175,7 +1206,7 @@ func LibraryFolderNameGTMaxLength() (result checkresult.Type, output string) {
 func IncorrectLibrarySrcFolderNameCase() (result checkresult.Type, output string) {
 	if library.ContainsMetadataFile(checkdata.ProjectPath()) && library.ContainsHeaderFile(checkdata.ProjectPath()) {
 		// Flat layout, so no special treatment of src subfolder.
-		return checkresult.NotRun, "Not applicable due to layout type"
+		return checkresult.Skip, "Not applicable due to layout type"
 	}
 
 	// The library is intended to have the recursive layout.
@@ -1270,7 +1301,7 @@ func RecursiveLibraryWithUtilityFolder() (result checkresult.Type, output string
 	}
 
 	if checkdata.LoadedLibrary().Layout == libraries.FlatLayout {
-		return checkresult.NotRun, "Not applicable due to layout type"
+		return checkresult.Skip, "Not applicable due to layout type"
 	}
 
 	if checkdata.ProjectPath().Join("utility").Exist() {
@@ -1288,7 +1319,7 @@ func spellCheckLibraryPropertiesFieldValue(fieldName string) (result checkresult
 
 	fieldValue, ok := checkdata.LibraryProperties().GetOk(fieldName)
 	if !ok {
-		return checkresult.NotRun, "Field not present"
+		return checkresult.Skip, "Field not present"
 	}
 
 	replaced, diff := checkdata.MisspelledWordsReplacer().Replace(fieldValue)
@@ -1327,15 +1358,3 @@ func nameInLibraryManagerIndex(name string) bool {
 
 	return false
 }
-
-func runRequiredLibraryPropertiesFieldCheck() (bool, string) {
-	if checkdata.LibraryPropertiesLoadError() != nil {
-		return false, "Couldn't load library.properties"
-	}
-
-	if checkdata.LoadedLibrary().IsLegacy {
-		return false, "Library has legacy format"
-	}
-
-	return true, ""
-}
diff --git a/check/checkfunctions/library_test.go b/check/checkfunctions/library_test.go
index dbefeddcf..098bd8e0b 100644
--- a/check/checkfunctions/library_test.go
+++ b/check/checkfunctions/library_test.go
@@ -107,7 +107,7 @@ func TestRedundantLibraryProperties(t *testing.T) {
 func TestLibraryPropertiesFormat(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Invalid", "InvalidLibraryProperties", checkresult.Fail, ""},
-		{"Legacy", "Legacy", checkresult.NotRun, ""},
+		{"Legacy", "Legacy", checkresult.Skip, ""},
 		{"Valid", "Recursive", checkresult.Pass, ""},
 	}
 
@@ -240,11 +240,11 @@ func TestLibraryPropertiesVersionFieldBehindTag(t *testing.T) {
 	}
 
 	testTables := []libraryCheckFunctionTestTable{
-		// TODO: Test NotRun if subproject
+		// TODO: Test Skip if subproject
 		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
 		{"Legacy", "Legacy", checkresult.NotRun, ""},
 		{"Unparsable version", "VersionFormatInvalid", checkresult.NotRun, ""},
-		{"Not repo", "Recursive", checkresult.NotRun, ""},
+		{"Not repo", "Recursive", checkresult.Skip, ""},
 		{"Tag name not a version", gitInitAndTag(t, TagNotVersionPath, "foo", true), checkresult.Pass, ""},
 		{"Match w/ tag prefix", gitInitAndTag(t, TagMatchWithPrefixPath, "1.0.0", true), checkresult.Pass, ""},
 		{"Pre-release tag greater", gitInitAndTag(t, TagPrereleaseGreaterPath, "1.0.1-rc1", true), checkresult.Pass, ""},
@@ -262,7 +262,7 @@ func TestLibraryPropertiesVersionFieldBehindTag(t *testing.T) {
 func TestLibraryPropertiesSentenceFieldSpellCheck(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
-		{"Not defined", "MissingFields", checkresult.NotRun, ""},
+		{"Not defined", "MissingFields", checkresult.Skip, ""},
 		{"Misspelled word", "MisspelledSentenceParagraphValue", checkresult.Fail, "^grill broccoli now$"},
 		{"Non-nil diff but no typos", "SpuriousMisspelledSentenceParagraphValue", checkresult.Pass, ""},
 		{"Correct spelling", "Recursive", checkresult.Pass, ""},
@@ -274,7 +274,7 @@ func TestLibraryPropertiesSentenceFieldSpellCheck(t *testing.T) {
 func TestLibraryPropertiesParagraphFieldSpellCheck(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
-		{"Not defined", "MissingFields", checkresult.NotRun, ""},
+		{"Not defined", "MissingFields", checkresult.Skip, ""},
 		{"Misspelled word", "MisspelledSentenceParagraphValue", checkresult.Fail, "^There is a zebra$"},
 		{"Non-nil diff but no typos", "SpuriousMisspelledSentenceParagraphValue", checkresult.Pass, ""},
 		{"Correct spelling", "Recursive", checkresult.Pass, ""},
@@ -283,6 +283,17 @@ func TestLibraryPropertiesParagraphFieldSpellCheck(t *testing.T) {
 	checkLibraryCheckFunction(LibraryPropertiesParagraphFieldSpellCheck, testTables, t)
 }
 
+func TestLibraryPropertiesEmailFieldAsMaintainerAlias(t *testing.T) {
+	testTables := []libraryCheckFunctionTestTable{
+		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
+		{"No email field", "MissingFields", checkresult.Skip, ""},
+		{"email in place of maintainer", "EmailOnly", checkresult.Fail, ""},
+		{"email and maintainer", "EmailAndMaintainer", checkresult.Pass, ""},
+	}
+
+	checkLibraryCheckFunction(LibraryPropertiesEmailFieldAsMaintainerAlias, testTables, t)
+}
+
 func TestLibraryPropertiesParagraphFieldRepeatsSentence(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
@@ -292,6 +303,18 @@ func TestLibraryPropertiesParagraphFieldRepeatsSentence(t *testing.T) {
 
 	checkLibraryCheckFunction(LibraryPropertiesParagraphFieldRepeatsSentence, testTables, t)
 }
+
+func TestLibraryPropertiesCategoryFieldUncategorized(t *testing.T) {
+	testTables := []libraryCheckFunctionTestTable{
+		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
+		{"No category field", "MissingFields", checkresult.Skip, ""},
+		{"Uncategorized category", "UncategorizedCategoryValue", checkresult.Fail, ""},
+		{"Valid category value", "Recursive", checkresult.Pass, ""},
+	}
+
+	checkLibraryCheckFunction(LibraryPropertiesCategoryFieldUncategorized, testTables, t)
+}
+
 func TestLibraryPropertiesUrlFieldDeadLink(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
@@ -310,7 +333,7 @@ func TestLibraryPropertiesDependsFieldNotInIndex(t *testing.T) {
 		{"Dependency not in index", "DependsNotIndexed", checkresult.Fail, "^NotIndexed$"},
 		{"Dependency in index", "DependsIndexed", checkresult.Pass, ""},
 		{"Depends field empty", "DependsEmpty", checkresult.Pass, ""},
-		{"No depends", "NoDepends", checkresult.NotRun, ""},
+		{"No depends", "NoDepends", checkresult.Skip, ""},
 	}
 
 	checkLibraryCheckFunction(LibraryPropertiesDependsFieldNotInIndex, testTables, t)
@@ -319,7 +342,7 @@ func TestLibraryPropertiesDependsFieldNotInIndex(t *testing.T) {
 func TestLibraryPropertiesDotALinkageFieldTrueWithFlatLayout(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
-		{"Not defined", "MissingFields", checkresult.NotRun, ""},
+		{"Not defined", "MissingFields", checkresult.Skip, ""},
 		{"Flat layout", "DotALinkageFlat", checkresult.Fail, ""},
 		{"Recursive layout", "DotALinkage", checkresult.Pass, ""},
 	}
@@ -330,7 +353,7 @@ func TestLibraryPropertiesDotALinkageFieldTrueWithFlatLayout(t *testing.T) {
 func TestLibraryPropertiesIncludesFieldItemNotFound(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
-		{"Not defined", "MissingFields", checkresult.NotRun, ""},
+		{"Not defined", "MissingFields", checkresult.Skip, ""},
 		{"Missing includes", "MissingIncludes", checkresult.Fail, "^Nonexistent.h$"},
 		{"Present includes", "Recursive", checkresult.Pass, ""},
 	}
@@ -341,11 +364,11 @@ func TestLibraryPropertiesIncludesFieldItemNotFound(t *testing.T) {
 func TestLibraryPropertiesPrecompiledFieldEnabledWithFlatLayout(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
-		{"Not defined", "MissingFields", checkresult.NotRun, ""},
+		{"Not defined", "MissingFields", checkresult.Skip, ""},
 		{"Flat layout", "PrecompiledFlat", checkresult.Fail, "^true$"},
 		{"Recursive layout", "Precompiled", checkresult.Pass, ""},
-		{"Recursive, not precompiled", "NotPrecompiled", checkresult.NotRun, ""},
-		{"Flat, not precompiled", "Flat", checkresult.NotRun, ""},
+		{"Recursive, not precompiled", "NotPrecompiled", checkresult.Skip, ""},
+		{"Flat, not precompiled", "Flat", checkresult.Skip, ""},
 	}
 
 	checkLibraryCheckFunction(LibraryPropertiesPrecompiledFieldEnabledWithFlatLayout, testTables, t)
@@ -444,7 +467,7 @@ func TestLibraryFolderNameGTMaxLength(t *testing.T) {
 
 func TestIncorrectLibrarySrcFolderNameCase(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
-		{"Flat, not precompiled", "Flat", checkresult.NotRun, ""},
+		{"Flat, not precompiled", "Flat", checkresult.Skip, ""},
 		{"Incorrect case", "IncorrectSrcFolderNameCase", checkresult.Fail, ""},
 		{"Correct case", "Recursive", checkresult.Pass, ""},
 	}
@@ -505,7 +528,7 @@ func TestIncorrectExtrasFolderNameCase(t *testing.T) {
 func TestRecursiveLibraryWithUtilityFolder(t *testing.T) {
 	testTables := []libraryCheckFunctionTestTable{
 		{"Unable to load", "InvalidLibraryProperties", checkresult.NotRun, ""},
-		{"Flat", "Flat", checkresult.NotRun, ""},
+		{"Flat", "Flat", checkresult.Skip, ""},
 		{"Recursive with utility", "RecursiveWithUtilityFolder", checkresult.Fail, ""},
 		{"Recursive without utility", "Recursive", checkresult.Pass, ""},
 	}
diff --git a/check/checkfunctions/sketch.go b/check/checkfunctions/sketch.go
index 7ba5a5711..4844a5d89 100644
--- a/check/checkfunctions/sketch.go
+++ b/check/checkfunctions/sketch.go
@@ -106,7 +106,7 @@ func PdeSketchExtension() (result checkresult.Type, output string) {
 func SketchDotJSONJSONFormat() (result checkresult.Type, output string) {
 	metadataPath := sketch.MetadataPath(checkdata.ProjectPath())
 	if metadataPath == nil {
-		return checkresult.NotRun, "No metadata file"
+		return checkresult.Skip, "No metadata file"
 	}
 
 	if isValidJSON(metadataPath) {
@@ -120,7 +120,7 @@ func SketchDotJSONJSONFormat() (result checkresult.Type, output string) {
 func SketchDotJSONFormat() (result checkresult.Type, output string) {
 	metadataPath := sketch.MetadataPath(checkdata.ProjectPath())
 	if metadataPath == nil {
-		return checkresult.NotRun, "No metadata file"
+		return checkresult.Skip, "No metadata file"
 	}
 
 	if checkdata.MetadataLoadError() == nil {
diff --git a/check/checkfunctions/sketch_test.go b/check/checkfunctions/sketch_test.go
index dc96dca3e..c0cc8fe1e 100644
--- a/check/checkfunctions/sketch_test.go
+++ b/check/checkfunctions/sketch_test.go
@@ -98,7 +98,7 @@ func TestPdeSketchExtension(t *testing.T) {
 
 func TestSketchDotJSONJSONFormat(t *testing.T) {
 	testTables := []sketchCheckFunctionTestTable{
-		{"No metadata file", "NoMetadataFile", checkresult.NotRun, ""},
+		{"No metadata file", "NoMetadataFile", checkresult.Skip, ""},
 		{"Valid", "ValidMetadataFile", checkresult.Pass, ""},
 		{"Invalid", "InvalidJSONMetadataFile", checkresult.Fail, ""},
 	}
@@ -108,7 +108,7 @@ func TestSketchDotJSONJSONFormat(t *testing.T) {
 
 func TestSketchDotJSONFormat(t *testing.T) {
 	testTables := []sketchCheckFunctionTestTable{
-		{"No metadata file", "NoMetadataFile", checkresult.NotRun, ""},
+		{"No metadata file", "NoMetadataFile", checkresult.Skip, ""},
 		{"Valid", "ValidMetadataFile", checkresult.Pass, ""},
 		{"Invalid JSON", "InvalidJSONMetadataFile", checkresult.Fail, ""},
 		{"Invalid data", "InvalidDataMetadataFile", checkresult.Fail, ""},
diff --git a/check/checkfunctions/testdata/libraries/EmailAndMaintainer/library.properties b/check/checkfunctions/testdata/libraries/EmailAndMaintainer/library.properties
new file mode 100644
index 000000000..9ad2514fa
--- /dev/null
+++ b/check/checkfunctions/testdata/libraries/EmailAndMaintainer/library.properties
@@ -0,0 +1,10 @@
+name=EmailAndMaintainer
+version=1.0.0
+author=Cristian Maglie <c.maglie@example.com>, Pippo Pluto <pippo@example.com>
+maintainer=Cristian Maglie <c.maglie@example.com>
+email=Cristian Maglie <c.maglie@example.com>
+sentence=A library that makes coding a web server a breeze.
+paragraph=Supports HTTP1.1 and you can do GET and POST.
+category=Communication
+url=http://example.com/
+architectures=avr
diff --git a/check/checkfunctions/testdata/libraries/EmailAndMaintainer/src/EmailAndMaintainer.h b/check/checkfunctions/testdata/libraries/EmailAndMaintainer/src/EmailAndMaintainer.h
new file mode 100644
index 000000000..e69de29bb
diff --git a/check/checkfunctions/testdata/libraries/EmailOnly/library.properties b/check/checkfunctions/testdata/libraries/EmailOnly/library.properties
new file mode 100644
index 000000000..d10347484
--- /dev/null
+++ b/check/checkfunctions/testdata/libraries/EmailOnly/library.properties
@@ -0,0 +1,9 @@
+name=EmailOnly
+version=1.0.0
+author=Cristian Maglie <c.maglie@example.com>, Pippo Pluto <pippo@example.com>
+email=Cristian Maglie <c.maglie@example.com>
+sentence=A library that makes coding a web server a breeze.
+paragraph=Supports HTTP1.1 and you can do GET and POST.
+category=Communication
+url=http://example.com/
+architectures=avr
diff --git a/check/checkfunctions/testdata/libraries/EmailOnly/src/EmailOnly.h b/check/checkfunctions/testdata/libraries/EmailOnly/src/EmailOnly.h
new file mode 100644
index 000000000..e69de29bb
diff --git a/check/checkfunctions/testdata/libraries/UncategorizedCategoryValue/library.properties b/check/checkfunctions/testdata/libraries/UncategorizedCategoryValue/library.properties
new file mode 100644
index 000000000..f311abbb3
--- /dev/null
+++ b/check/checkfunctions/testdata/libraries/UncategorizedCategoryValue/library.properties
@@ -0,0 +1,9 @@
+name=UncategorizedCategoryValue
+version=1.0.0
+author=Cristian Maglie <c.maglie@example.com>, Pippo Pluto <pippo@example.com>
+maintainer=Cristian Maglie <c.maglie@example.com>
+sentence=A library that makes coding a web server a breeze.
+paragraph=Supports HTTP1.1 and you can do GET and POST.
+category=Uncategorized
+url=http://example.com/
+architectures=avr
diff --git a/check/checkfunctions/testdata/libraries/UncategorizedCategoryValue/src/UncategorizedCategoryValue.h b/check/checkfunctions/testdata/libraries/UncategorizedCategoryValue/src/UncategorizedCategoryValue.h
new file mode 100644
index 000000000..e69de29bb