Quote their email for me please, the 2012 application guide tells you to write each subject individually. I'm perfectly happy to be proven wrong (mostly because it would boost my GPA)
In the preceding email I quoted that section of the guide, the reply:
Remember those instructions are for applicants to calculate a rough GPA for their own information. GEMSAS uses percentages where they have been supplied.
Kind regards
Catherine
Rejoice Russ 
Obviously you have misinterpreted the email. Some universities only provide a grade on the transcript.
Here's an example (refer to page 32 GMAC guide). Let's take a student completing a BSc at University of Wollongong. He gets a 81 for subject and ONLY a 'D' grade appears on the transcript. Now, notice that for UoW 75-84% is a D. Since 75-79 corresponds to a GPA of 6.5 and 80+ corresponds to a GPA of 7.0, how would GEMSAS know whether to award the student a 7.0 or 6.5 since ONLY 'D' grade appeared on the transcript? Therefore according to Column B, if ONLY a D grade was awarded, the student will be awarded a 6.75. According the the email, if BOTH the 'D' grade and and score of 81% appeared on the transcript, GEMSAS will take the percentage and convert it to GPA form, hence awarding the student a GPA of 7.0.
Hope this clears your doubts.