You can create default pick release rules that are applied at pick release in the Release Sales Orders window. Each rule can be set up with its own set of unique pick release parameters depending on the pick release criteria required.
When pick release is run, the pick release is performed based on the parameters set up in the selected pick release rule. For example, you can create a specific rule that pick releases only backordered lines.

Note: Although you can also enter the pick release criteria at pick release time without creating a rule, creating a rule is more efficient if you frequently run the same pick release. Also, note that it is required when releasing using SRS or when using the Auto Pick Pack and Ship features.