At this moment in HEAT 2015.1.2, it is not possible to add a validation rule in a Request Offering template field configuration.
This article describes how to add a validation rule for a specific field. In this case we demonstrate how to validate that a date selected is not on a weekend, but the same steps would be valid for any type of validation.
1.- In the Request Offering, name the date field as "NoWeekendDate" (Note: any Request Offering with a similar field name will be validated with the same rule):
2.- In the ServiceReqParam object, add the following validation rule:
$(if ParameterName == "NoWeekendDate"
then if LocalDayOfWeek(ParameterValue) == 1 ||
LocalDayOfWeek(ParameterValue) == 7
3.- When the user submits the Service Request, if he has chosen a Saturday or a Sunday, he will get the following message. (Note: the message includes the RecId but it is under investigation by our development team):