Caption - %ca[title]

%ca defines the title for a format window. The title is supplied as a standard character string.

For example:

i=winio@('%ca[Error]')

The caption will be re-drawn whenever the window is refreshed. This means that if the title is supplied in the argument list (signified by the "@" character in the format string) then the window title can be changed dynamically by changing the contents of the string and calling window_update@.