The sdComment command is used to hide portions of articles.  This can be used to hide portions of an article that aren't ready, leave comments for other editors, etc.  For example, the following paragraph contains the word "comment" 4 times, but 3 of them are between sdComment tags:

This paragraph contains a comment that can't be seen.

Here is the same paragraph again with the comment forced to be visible:

This paragraph contains a {sdComment}comment comment comment{/sdComment} comment that can't be seen.

 

 

Note that sdComments can contain sdMacros commands, but they must be properly nested to avoid errors.  Commands embedded in this way will not be processed.