Well I've been lurking and learning for years. I just haven't had much to add to anything since everyone around here is pretty damned intelligent.
But now that I see this I gotta pipe up and say that way way back in my 20's this paintball team I used to run with used very similar signals to the BATF ones posted here, but we also had a few hand signals too. check it out:
1) yeah I know there is wind. I have strong wind here all year long.
2) the ranks are to help you divide for your span of control. You could use daisy, tulip, rose and marigold for all it matters.
3) different hand signals are for different purposes. To prevent the endless confusion I get with these....
You won't pass the CPL signal for instance and 10 other signals back through a line on patrol. If you are patrolling you will probably only use 10-15 of these.
If you are part of a group of 16 people it is divided into 4 groups of 4 person fireteams. Each fireteam is 2 - 2 man buddies.
If you have 4 groups of 4 people each, 1 person is a CPL in each group in name only, so you can control each group through him. The CPL from each group comes up and you use the hand signals to silently communicate your plan of action. They then go back and tell the others. This way you don't have to instruct 15 other people, you tell 3 people everything such as the ambush scenario I use at the end and they do the rest. It is better then saying you, you, you and you go do this and you, you, you and you go do this.
It is extremely hard to control 16 people but if you divide like this you could control 1000. There was a reason why God chose to divide the people into 10s, 100s, 1000s.
Recon, security and other hand signals. If you come to a road crossing or danger area, depending on the procedure you use to cross, you signal for the security team to come up (near and far) and the recon team to cross the danger area, search and provide security.
I was originally taught that your job as these areas was dependent on your position in line but if you change your position your job changes, you forget your job etc. Its easier to have it set up in your OPORD that 1 of your groups of 4 is the security element (danger areas, ambush, etc) and another is the recon element and they do those jobs as long as they are still assigned to them.
This is to just explain why those hand signals exist. The whole OPORD, METT-T thing is another topic.