"safe" signal

[Andy]

First of all, I only work HS volleyball using NFHS rules.

I have noticed several of my fellow officials using a "safe" signal to indicate that there is nothing to call on a particular play.

I am wondering where this might have come from. I have never been told to use this signal in any VB training I have been to. Now, our training for HS officials the last few years has been sorely lacking, but I still have not been instructed to use this signal from any official source.

I'm not referring to the "legal back row attack" signal as shown in the NFHS book using a single arm on one side of the net.

Did the use of the "safe" signal originate in other VB codes or sanctions?