why banks dont give long term extension, page-25

As far as property goes there is no such thing as 'Mark to Market' in Australia.

You're think of Australian Accounting Standards Board publication 136 (AASB 136) on Impairment Testing. Impairment Testing is a very complicated field, but suffice to say, an asset or group of assets in a 'cash generating unit', like a shopping centre, cannot be revalued down below:
- recoverable amount;
- fair value less cost to sell;
- costs of disposal; or
- value in use.

So even if the fair value less cost to sell went very low, say $100, then they could not revalue the shopping centre down to that value because its 'value in use', which is the discounted cash flows from the centre, would presumably be much greater.

Hope this helps.