Hyperlink info can be added labels (or parts of labels). This is useful when the resulting image is embedded in web pages. Hyperlinks are not (yet) exported into a PDF or SVG file. Currently link information can be extracted via the -T ismap command-line option, which provides an NCSA formatted ismap file. Such files are used by Doxygen, for example, so this feature is most applicable to Doxygen integration. (If you specify a link target as \ref Name then Doxygen will point to a function or class named Name in the documentation created by Doxygen.)

On the Windows GUI, links are visible and if they represent a URL they are clickable.

There are two ways to add hyperlink information. First, any element having a label can be added the url attribute. The value of the attribute (which you usually need to put between marks) is the target of the link. This makes the entire label point to the target. Second, you can also use the \L() escape in pairs, making only the text between them to point to the link target. The target of the link shall be specified as the parameter to the first \L() escape. In this case the link target may not contain closing parenthesis^[25]. Using this second method it is possible to add several links to (different parts of) the same label. You cannot use both mechanisms to the same label. Note that you can only use the second method to add hyperinks to box tags.

Links also change formatting. In the plain design, they became blue and underlined. This is governed by the text.link_format chart option and attribute. Any formatting escape sequence you specify as value to this chart option or attribute will be applied at the beginning of the link text and de-applied at the end.