You can create rules for certain types of online entry form field. For example, you might want an "animal date of birth" to be within a certain date range for a certain class.
Here's how to do this:
1.) Goto to Utilities > Entries > Entry Forms Setup
2.) Load the entry form that you would like to add the rule to.
3.) Goto the Entry Form Field tab.
4.) Click on the entry form field that you would like to add a rule to. Only numeric or date fields can have rules applied.
5.) Click the "Online Validation Manager" button.
6.) A window titles "Online Form Field Validation Rules" will be shown.
7.) Put in the range that you would like to apply, for example if the "Date of Birth" needs to be in 2012, put in "01/01/2012" and ''31/12/2012".
8.) Next click the classes that you would like the rule to be applied to in the bottom grid.
9.) Once both of these are select, click the "Apply Rules" button to create the rules.
10.) Publish entries to the web modules and the rule will then be applied online.
Done!