> > what I meant was that we might want to distinguish between those that > show information and those that show traffic signs to which you must obey. >
There is no way to distinguish this, unless you have access to the programming, and a fair number are automated to flex to traffic conditions. The various American standards show these as Dynamic Messaging Signs, with other older content showing "character-matrix" Variable Messaging Signs, mostly with the 'text only' as VMS and the more modern "full-matrix" graphic technology as DMS. Other sources say the opposite. In Europe, they are still mostly known as VMS, there is some discussion here: See "Dynamic message signs: differences between Europe and North America" https://www.traffictechnologytoday.com/opinion/dynamic-message-signs-differences-between-europe-and-north-america.html The international ISO standards for intelligent traffic systems say "NOTE: A Variable Message Sign is also named dynamic message sign. Both terms are considered as synonyms and can be used interchangeably." On that basis, the Solomon's choice ( https://en.wikipedia.org/wiki/Judgment_of_Solomon ) would be to use to tag them something along the lines of "DMS/VMS","DMS-VMS", because almost every source (North American, British, European, etc.) I found uses that sort of contraction as the convention, including the manufacturers. For any sub-tagging, the standards bust out further details according to the display tech, fixed or mobile, size, etc. The ones that change state according to a single variable or condition, like only speed, or lane open/closed, chains required, road flooded, etc. IMHO are more akin to the normal signs, in that even a normal parking sign has 'variability' of states built into the message. Ref: https://www.nema.org/Standards/Pages/Hardware-Standards-for-Dynamic-Message-Signs-with-NTCIP-Requirements.aspx https://blog.ansi.org/2017/02/dynamic-message-signs-dms-electronic-road/#gref Michael Patrick Data Ferret
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