Custom regional limitations required

As per: http://www.steamgifts.com/discussion/vl7rF/out-of-luck-on-gifting-this

Some especially greedy publishers just LOVE to invoke their own made up locks, like Resident Evil Revelations 2 Complete Season has different subids which have limitations for EU/America even if bought in a ROW region --- so the gift DOES NOT have any restrictions but cannot be activated in specific countries because of the flag PurchaseRestrictedCountries.

As aworkaround it would make sense to be able to specify SubID on the giveaway page so SG can fetch specific restriction data via SteamAPi or steamDB, does not matter. Since the site already has built-in functionality for users to specify country I see no issues for it to work as intended in the end.