Just out of interest I have been investigating how small I can make a viable application which will work with OS X 10.4, 10.5 and 10.6.
I have produced several applications below 50 bytes. The simplest consists of only the following 36 byte file at say.app/Contents/MacOS/say
#!/bin/bash
osascript -e 'say "ok"'
Unfortunately the following 344 byte icon is the smallest distinctive one I have found which will work in the Dock:
69 63 6E 73 00 00 01 58 69 63 73 23 00 00 00 48
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 7F FE 7F FE 60 06 60 06 60 06 60 06 60 06
60 06 60 06 60 06 60 06 60 06 7F FE 7F FE 00 00
69 63 73 38 00 00 01 08 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 B9 B9 B9 B9 B9 B9 B9
B9 B9 B9 B9 B9 B9 B9 00 00 B9 B9 B9 B9 B9 B9 B9
B9 B9 B9 B9 B9 B9 B9 00 00 B9 B9 00 B9 00 00 00
00 00 00 00 BB B9 B9 00 00 B9 B9 00 B9 00 00 00
00 00 00 00 00 B9 B9 00 00 B9 B9 00 B9 00 00 00
00 00 00 00 00 B9 B9 00 00 B9 B9 00 B9 FF FF FF
00 00 00 00 00 B9 B9 00 00 B9 B9 00 00 FF FF FF
00 00 00 00 00 B9 B9 00 00 B9 B9 00 00 FF FF FF
00 00 00 00 00 B9 B9 00 00 B9 B9 00 00 00 00 00
00 00 00 00 00 BB B9 00 00 B9 B9 00 00 00 00 00
00 00 00 00 00 B9 B9 00 00 B9 B9 00 00 00 00 00
00 00 00 00 00 B9 B9 00 00 B9 B9 00 00 00 00 00
00 00 00 00 00 B9 B9 00 00 B9 B9 B9 B9 B9 B9 B9
B9 B9 B9 B9 B9 B9 B9 00 00 B9 B9 B9 B9 B9 B9 B9
B9 B9 B9 B9 B9 B9 B9 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
This icns icon consists of an ics# 16x16 mask and monochrome image plus an ics8 16x16 8 bit colour image. My understanding is that Dock icons must include at least one image with a mask but I don't understand why it does not work without the ics8 colour image.
Image formats are specified at: https://en.wikipedia.org/wiki/Apple_Icon_Image_format
Does anybody know if smaller icon files can be made to work in the Dock and if so how?