The Forth words are described in this section in the glossary notation that has become a de-facto standard for Forth texts:
word Stack effect wordset pronunciation
after, where before and after describe the top of
stack entries before and after the execution of the word. The rest of
the stack is not touched by the word. The top of stack is rightmost,
i.e., a stack sequence is written as it is typed in. Note that Gforth
uses a separate floating point stack, but a unified stack
notation. Also, return stack effects are not shown in stack
effect, but in Description. The name of a stack item describes
the type and/or the function of the item. See below for a discussion of
All words have two stack effects: A compile-time stack effect and a run-time stack effect. The compile-time stack-effect of most words is – . If the compile-time stack-effect of a word deviates from this standard behaviour, or the word does other unusual things at compile time, both stack effects are shown; otherwise only the run-time stack effect is shown.
gforth-internal as word set.
describes words that will work in future releases of Gforth;
gforth-internal words are more volatile. Environmental query
strings are also displayed like words; you can recognize them by the
environment in the word set field.
The type of a stack item is specified by the character(s) the name starts with: