The term man(ual) page refers to a particular markup language originating on Unix systems. The particular markup language is also known as *roff - a family of markup languages designed to do presentation markup in ASCII text with an eye towards typesetters (troff) or plain text (nroff).
CL thinks of it instead as documentation content--"That is what you need? Look in the man page for ioctl(2)" is an example of this usage.
The manual pages for Tcl are available on-line, of course. [L1 ].