Built-in editor

COMIS provides a built-in editor which is automatically invoked by the interpreter when an error is detected. The COMIS built-in editor is similar to the VAX line-mode EDIT/EDT. A line can be referenced by its line number. The INSERT and DELETE commands change a the line numbering. To operate on a set of lines it is possible to specify a line range in the following forms:

N1:N2

specifies the set of lines from N1 to N2, where N1<N2 or N1>N2.

N

specifies N-th line from the beginning of the file.

+N

specifies +N-th line from the current pointer position.

-N

specifies -N-th line from the current pointer position.

The character ``F'' is recognized as the first line of the routine and the character ``L'' is recognized as its last line; ``W'' is recognized as ``F:L''.