http://www.australianstrampcatalogue.com

There are two different types listed below, a large puncture of fifteen stamps and a small puncture of sixteen stamps, the large puncture was discontinued after it was found that the stamps tended to tear apart, so a smaller puncture was then adopted, but even this proved a problem, eventually a printed OS was adopted by the Commonwealth, but the individual States continued to use the punctured type of OS for many years, in the State of Victoria's case, I have a stamp in my collection, issued in 1986 that was punctured VG which stands for Victorian Government.

First Issued 1913 - Watermark 42 - Large Crown over letter "A"
The perforation has been listed as 12 or 11½ x 12, the actual size is 11.7 x 11.8 closer to 11¾ or 15 holes per inch.
All stamps below are listed in value order as date of issue is impossible to determine without a date on the stamp, even then the stamp could have been about for months before being used, there are five stamps in this series that elude me, although I have not been actively searching for them either.

Punctured Large "OS"

1-1-1 OS ½d Green, Large OS Official;
1-2-1 OS 1d Red, Large OS Official;
1-3-1 OS 2d Grey, Large OS Official;
1-4-1 OS 2½d Blue, Large OS Official;
1-5-1 OS 3d Olive, Large OS Official;
1-6-1 OS 4d Orange, Large OS Official;
1-7-1 OS 5d Brown, Large OS Official;
1-8-1 OS 6d Blue, Large OS Official

1-9-1 OS 9d Violet, Large OS Official;

1-10-1 OS 1/- Green, Large OS Official;
1-11-1 OS 2/- Brown, Large OS Official;
1-12-1 OS 5/- Grey/Yellow, Large OS Official;
1-13-1 OS 10/- Grey/Pink, Large OS Official;
1-14-1 OS £1 Brown/Blue, Large OS Official;
1-15-1 OS £2 Black/Red, Large OS Official

Punctured Small "OS"

1-1-1 SOS ½d Green, Small OS Official;
1-2-1 SOS 1d Red, Small OS Official;
1-3-1 SOS 2d Grey, Small OS Official;
1-4-1 SOS 2½d Blue, Small OS Official;
1-5-1 SOS 3d Olive, Small OS Official;
1-6-1 SOS 4d Orange, Small OS Official;
1-7-1 SOS 5d Brown, Small OS Official;
1-8-1 SOS 6d Blue, Small OS Official;

1-9-1 SOS 9d Violet, Small OS Official;
1-10-1 SOS 1/- Green, Small OS Official;
1-11-1 SOS 2/- Brown, Small OS Official;
1-12-1 SOS 5/- Grey/Yellow, Small OS Official;
1-13-1 SOS 10/- Grey/Pink, Small OS Official;
1-14-1 SOS £1 Brown/Blue, Small OS Official;
1-18-1 SOS £1 Grey, Small OS Official;
1-15-1 SOS £2 Black/Red, Small OS Official;