[Last modified: Sept 94]

Answer: UIL is the acronym for "User Interface Language", a Motif standard
which permits separation of the user interface from application code.  UIL is
a textual description of the user interface which is compiled into binary form
called UID ("User Interface Definition") using the Motif-provided compiler
called "uil".

It is important to realize that UIL is a static description of the UI in that
connections between buttons and the dialogs they invoke, for example, is not
expressed here; dynamic UI behavior appears in C code.

The Period Table of Widgets, called "periodic" (delivered by many Motif
vendors) is an example of a UIL application.

There are many advantages and disadvantages of UIL applications.  A few of the
advantages are:

UIL is a standard format which encourages separation of the user interface
from application code.

UIL can be read and/or written by many of the GUI builders and UIMS tools
mentioned elsewhere in this FAQ, making your interface portable (to a degree)
across builder tools.

UIL is a much better language than C for defining a widget hierarchy: in C,
the widget hierarchy is expressed "linearly" by referencing a previously-
created parent widget when creating a child widget; in UIL, widget trees are
defined more naturally using nesting.

With UIL, you separate the definition of the widget tree from the application.
You can make major changes to the look-and-feel without re-building the
application.


It is possible to write a "general-purpose" application that defines a library
of callbacks.  The application may "execute" any UIL file that references
callbacks from the library.


For a good UIL reference, see "Motif Programming Manual", Volume 6A, published
by O'Reilly and Associates. [See "BOOKS" for details.]