A segment name must contain only lower-case alphanumeric characters (a-z, 0-9), hyphens (-), or underscores (_). There can be no spaces in a segment’s name.
The insert clause is to set the rules for the segment. You can create a segment for a particular domain, date or action by inserting a clause.
Below is a sample of an AOL segment that was created. The segment name is called “aol”. The description is called “AOL members of list. A clause was inserted for “Domain_=’aol.com”