[edit]
Graphical User Interface
As opposed to command line input. PSYC supports this type of approach using _request_do.. methods also described on the command page.
This typically affects clients but also webchats.
These days, HTML is the most established remote GUI technology around - even though it was originally intended to rather be semantically rich than visually well-defined. Several PSYC clients prefer HTML-based GUIs over traditional user interface technologies.
See also Wikipedia:GUI.