Check Function Validate PostalCode

Data Integrity Checks
Summary:	Validates that Postal Code field only contains characters in format allowed for a postal code
Related:	[[Postal Code field]]
Firmness:	hard check
Timing:	complete
App:	not entered
Coding:	Function Validate_PostalCode
Uses L Problem table:	not relevant for this app
Status:	implemented
Implementation Date:	2016-03-24
Backlogged:	true

Implementation date was earlier than that when we had this in a tmp field; it has been checked for longer than this.

Implemented in Function Validate_PostalCode() and Function is_valid_postalcode

will reject empty field
will reject invalid postal code (ie not PC Like "[A-X]#[A-Z]#[A-Z]#")

Declined portion of checks

Cross-checks of PC against Province were implemented at some point but then discontinued due to false positives. Function pc_province_match. Comments in there:

' 2016-07-25
' it was decided long ago not to check this by the steering committee because
' it gave false positives.
' 2016-11-14 emailed team to find out if we should revisit