An hyText file (usual extension .xlp consists of plain ASCII text, with blocks marked with codes as in the following:
\hy-X{Y}{Text}
where X is the block type and Y is the block identifier (unique within a file). The block type indicates the style of the block (font, colour, section), where the mapping between type and style is defined in a table (an instance of wxHyperTextMapping.
Note that blocks may be nested, in which case any styles in an inner block which have been the assigned `default' characteristic will inherit the style from the outer block.
At the end of a file there is an optional index section, for example:
\hyindex{ "wxWindows Help" 101 102 "wx.xlp" 114 115 117 118 120 121 123 124 }
The first line indicates the start of the index, the second line is a title for the help file, subsequent lines (until a closing curly bracket) indicate the link between two block identifiers, with an optional filename after each pair of (long) integers.
This index is only stored and read by hyText, and must be accessed by the application in order to allow the user to actually traverse links.