Smartlist Editing:
http://wiki.jriver.com/index.php/Smartlists() is for OR, [] is for AND. When no brackets are present, AND is the default.
You use AND when you want to have all rules satisfied simultaneously, i.e. all conditions must be satisfied in order for a program to be selected. You use OR if you want one of the condition to be satisfied, but not necessarily all of them.
For example,
Season is 1, OR Season is 2, OR Season is 3
A given program can not satisfy all of the three conditions. So it would not make sense connecting them with AND. With OR, a program with Season 1 will be picked, so will a program with Season 2, etc.
Season is less or equal to 5 AND Season is greater than 0
This, in MC's expression language is "[Season]=<=5 [Season]=>0", specifies that the two conditions must both be satisfied. The first one says Season must be less than or equal to 5. So seasons 1, 2, 3, 4, 5 satisfy it, but not Season 6. The second condition says Season must be larger than 0. So Seasons 1, 2, 3, 4, 5, and 6 and above all satisfy it. But only 1, 2, 3, 4, and 5 satisfy both.
[Season]=>0 is needed to filter out all programs that has no Season field (empty field) as empty value is considered 0.