So I made a pocket reference card to fold up and stick in my wallet for just such an occasion! Feel free to add this to your toolbox!
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In the interest of keeping it a "pocket" reference guide, statute numbers have been left off, 51% signs were not mentioned, and only the information most pertinent to determining a sign's validity was included.
Disclaimer: I am not condoning a LTC citizen ignoring a sign "because it's not valid." I merely want to facilitate the uploading of accurate information to Texas3006.com.
Edit 1/25/16: Uploaded revised version of cards to reflect proper language. "ALL CAPS" changed to "block letters (i.e. no cursive)."