A comment starts with `%%'. It is terminated either by another `%%' on the same line, or by a subsequent line that starts with some symbol other than `%%' (ignoring spaces). Thus the usual pattern is:
CASL symbols...%% first comment line... %% maybe more comment lines... %% last comment line... %% CASL symbols...
allowing also a short comment to occur in the middle of a line:
CASL symbols...%% short comment... %% CASL symbols...
A comment applies to the longest preceding complete construct (ignoring intervening separators such as semicolons), if there is one, and otherwise to the smallest enclosing construct. Thus a comment between BASIC-ITEMs in a list thus applies to just the preceding BASIC-ITEM (rather than to the whole preceding list) regardless of whether it comes before or after the separating semicolon. A comment at the start of the list applies to the whole list. An exception to the above is a comment that finishes with `:', which always applies to the longest following complete construct.
Further details concerning the use of formatting instructions in comments are given in [BCKB+98].