Keywords (User-Defined) Advanced Search

[armsys]

I'm confused by the options offered by Keywords (User-Defined) Advance Search:
exists
equals
less than
less than or equal to
great than
greater than or equal to

"Exists" can be plainly understood.
How about others?
Multiple info items can be assigned with multiple user-defined keywords.
How are these options "equals", "less than", "less than or equal to ", "greater than" and "greater than or equal to" supported to work?
For example, what would "great than" compare for? Does it mean "greater than" number of keywords?
Please help. Thanks.