How to get Transaction Variant Tcode in a transaction

Dear Sir,

We have created a transaction variant "ZMB1A" for a dialog transaction MB1A . During execution of ZMB1A , by using USER-EXIT we want to know the name of transaction being used . For this in a USER-EXIT associated with MB1A , we are using SY-TCODE , but the problem is that SY-TCODE is returning MB1A and not ZMB1A .

Kindly guide us , how can we get the actual transaction name i.e ZMB1A .

With regards

B Mittal