- Change parameter order in \providelength to match \setlength.

- Remove Part name from appendix and back matter headers.

packages/Header.sty

@@ -17,14 +17,17 @@
 \setlength{\outsideheaderoffset}{1.0in}
 
 \NewDocumentCommand{\chapappname}{}{Chapter \thechapter{}: }
+\NewDocumentCommand{\partlabel}{}{\partname{} \thepart{}: \parttitle}
 
 \NewDocumentCommand{\Appendix}{}{
 	\appendix
 	\RenewDocumentCommand{\chapappname}{}{Appendix \thechapter{}: }
+	\RenewDocumentCommand{\partlabel}{}{}
 }
 
 \NewDocumentCommand{\BackMatter}{}{
 	\RenewDocumentCommand{\chapappname}{}{}
+	\RenewDocumentCommand{\partlabel}{}{}
 }
 
 \NewDocumentCommand{\parttitle}{}{}
@@ -35,13 +38,13 @@
 	\ifthenelse{\boolean{isElectronic}}{
 		\fancyhfoffset[L]{\insideheaderoffset}
 		\fancyhfoffset[R]{\outsideheaderoffset}
-		\fancyhead[L]{\partname{} \thepart{}: \parttitle}
+		\fancyhead[L]{\partlabel}
 		\fancyhead[R]{\chapappname{}\leftmark}
 
 		\fancyfoot[R]{\thepage}
 	}{
 		\fancyhfoffset[LE,RO]{\outsideheaderoffset}
-		\fancyhead[LE]{\partname{} \thepart{}: \parttitle}
+		\fancyhead[LE]{\partlabel}
 		\fancyhead[RO]{\chapappname\leftmark}
 
 		\fancyfoot[LE,RO]{\thepage}