20.4.1.1 Understanding how browse macros vary by file position

Default definitions of browse macros <$_prev> and <$_next>, and the meanings of the macro variables these macros employ, vary according to:

whether the macros produce text links or buttons (see §20.4.2 Choosing buttons versus text links for a browse sequence)

the sequential position of the HTML file in which the macros are invoked; one of:

a split file that is neither the first nor the last split from its FrameMaker file

the first file split from any but the first FrameMaker file

the last file split from any but the last FrameMaker file

the first file split from the first FrameMaker file

the last file split from the last FrameMaker file.

You can change any of the definitions by changing the macro code assigned to appropriate navigation keywords; see §20.4.4 Modifying macros <$_prev>, <$_next>, and <$_top>.