Ann: Trading Halt, page-46

It's a legitimate precaution ASX companies commonly take. In the process of finalising the collection of data, statement etc, a number of people in the organisation may have access to this information prior to its release to the ASX. To avoid the potential for a leak, and the market trading unfairly as a result, they may choose to place it in a trading halt while they complete this.

Nothing nefarious or sneaky about it. I don't see it as a 'tactic'. It's just a precaution some companies take.

Edit: Just like to add, that this also helps avoid unnecessary bad perception that may arise. The share price of companies like PNV can be quite volatile and on random days it can fluctuate a lot. If those price fluctuations just coincide with an ASX announcement, they may get ASX questions. Not a problem, but just annoying, and potentially creating unnecessary/incorrect perceptions of leaks... so why bother risk it? If I were the chairman, I'd do the same. Nothing to lose in just halting trading for a short period to finish compiling the figures, getting it checked and writing up the announcement.