# TO -- hypertext documentation link

## Synopsis

• Usage:
TO x
• Inputs:
• x, a documentation key
• Outputs:
• an instance of the type TO,

## Description

TO "x" produces a hypertext link to the documentation page labeled x.

See also hypertext. The word hypertext in the previous sentence is an example of the use of TO.

The special form TO {"x", "s"} produces a hypertext link to the page labeled x, but with the string "s" appended to the string "x" at the point where the reference occurs. This form is needed because in some modes of output the link is indicated with a section number in brackets.

The special form TO (f,X) produces a hypertext link to the page documenting the method used for applying the function f to an argument of class X. For more arguments, use TO (f,X,Y) or TO (f,X,Y,Z).

The special form TO [f,X] produces a hypertext link to the page documenting the optional argument named X for the function f.

If TO x is an entry in a UL, then it is treated as TOH x, and headlines are added automatically.