Abbreviation for Hydraulic

[jerry1423]

Does anybody know the engineering standard abbreviation for the word Hydraulic?
I found on-line the abbreviation is hydraul. (the period is part of the abbreviation)
This makes no sense to me because hydraul. is (8) characters (with the period)
and the full-word Hydraulic is (9) characters. There virtually no benefit to using the abbreviation.
I saw at a different place on-line the abbreviation is HYD but I do not understand why it is all caps, because it looks like an acronym.
I also do not understand why the first abbreviation requires a period, as most leave it out.
I am old-school and can be particular about things like this. I am working on company standards, so I want to support myself if asked why I did it a certain way.

Jerry J.
UGV5-NX1899

 

[Stick.]

I haven't seen a standard way to abbreviate "hydraulic". In my opinion, regardless of if you find a "standard" abbreviation or not, the best practice would be to define whatever abbreviation you use somewhere in your company standards. If you only have a standard or two where this abbreviation will pop up, then define it in each standard. If you will use it all over the place, consider a separate standard of internal abbreviations, definitions, etc.