I have to restrict below entries by REGEX function in validation rule. Please let me know how to do that. I am unable to replicate the case. I need to put that part in below Validation Rule.
String formats to restrict
P O B
POB
P OB
PO B
Validation Rule existing
AND(OR(REGEX(Name,".*(?i)(p[. ]?o([. ]?|st[ ]?office))[. ]?box.*")),
NOT(ISPICKVAL(Address_Type_abv__c,"Mailing")))