Not New High Visibility

So it's quite usual to plentiful signs at building sites and suchlike where the sensible of wearing safety clothing is a must....hard hats, safety shoes and high visibility clothing especially.  In this high vis sign, rather than use 'wear', it's 'worn'.  That can also also mean 'not new' of course, which can rather convey the message that the high vis clothing must not be "new" high vis clothing.

While we might be used to hearing the abbreviation of "visibility" to "vis", it's also usual in the written form to abbreviate the "High" to "Hi".  In the first abbreviation it's a shorter written and different sounding solution, without a strong different meaning.  Technically though Vis is a small Croatian island in the Adriatic sea, with a town of the same name and a population of around 3500, and it's the Vatican's press office - the Vatican Information Service.   At any rate "vis" does have some other very specific meanings, but not common place enough to matter here.

On the other hand, abbreviating "High" to "Hi", is different, perhaps one of the most common words of greeting in the western world.  The immediate distraction to think "hello" is mostly avoided here through the visual clue of the clothing and the association with "vis". In some cases the "High Visibility" is strangely abbreviated to "Hi Viability", and that starts to feel like a typo.