This is a critical point, but today, a fellow official pointed out to me that by the book, the trail should only mirror the lead's successful 3-point shot signal and not the 3-point attempt signal. I am certain that is contrary to the way I was taught, but that does seem to be what the book says. Is that the practice other places? I will be curious to watch other officials in my area, but I am willing to bet that most are mirroring the attempt signal.

In two person mechanics that is correct. The T does not mirro the attemp, only the TD signal. We were recently talking about this in another thread.

This is how I've done it.

Here, too.

As the others have said, your fellow official is correct in FED 2-person.

In NCAAW 3-person, trail mirrors the attempt. L doesn't signal that the shot is successful.

In NCAAM, it's NA -- L doesn't signal the attempt or the success.

I submit the L doesnt but there are times s/he can signal or mark the attempt based on the sitch...

Example: Transition situation where L has a clear look and the T is not all the way into position.

But NORMALLY, the L doesnt signal on 3s.

I agree, this applies to HS too.

FIBA-

2 man
Trail signals attempts
If the ball is in the area of lead or right between lead will signal 3 point attempt. Trail will then mirror the signal, if the basket is good, trail will signal made 3 point, lead will still only hold one hand up!

3 man
same thing for the lead/trail areas

C/T mirror made 3 points (not attempts)

One of the main rationales for T mirroring a 3-point attempt initially signalled by L is that someone sitting at a stats table is charting whether the shot attempt was a "2-point" or "3-point" attempt. An indication by L (who is tucked beyond the end of the court) may not be readily or easily noticed by such Stat Keepers.

Statkeepers are not part of the game, no need to mirror an attempt.

When basket is made (or missed), lead should drop three-point attempt signal.

The reason for mirroring is that the scorekeeper shall see, stats are irrelevant. But the board must know if the score is 2 or 3, and they can in most cases not see the L, therefor T mirrors.

Yes offcourse, but hold it up for a second or two confirming the score (just like T will do but with two hands)

that's what I've been taught (and see officials do) anyway

I don't know what "lobo" is promoting, but his link goes to a site called "bitefight", not to an Official Forum page. I wouldn't click on it unless you know what bitefight is. I'm alerting the mods now.