Trump, there are two types of "red tags."
One is a seal the PoCo puts on the meter, same as their usual seal, but red in color. This is used when power is shut off for safety or non-payment reasons.
The other is an 4x6" (or so) piece of paper (or sticker) place on a structure by the building inspector, and says "Cease and Desist all Work". The most common reason for such a tag is not having a permit.
Haven't seen the second for a while...But I will take a pic when I do.
Oh, our PoCo has another special tag....the purple one. That is used when there are serious issues, such as power theft, and that seal can only be broken by their investigator, and not the "faults" or "troubleman."