Originally Posted by rednichols

You've got it right there :-). A field holster is something set up ("rigged" it used to be called) to be worn outside for rough duty; and has a belt attachment for a wide belt, a strap or flap, full coverage for the gun (more with a flap), thick leather, overall a bit heavy, angle is usually vertical, balance is below the belt, etc.). A concealable has entirely different specs you'd agreed; a uniform holster much narrower ones (carry angle becomes important, for example); military even narrower.

"Back in the day", if one wanted to 'splain these things over the phone, we'd have called it a Hunter-type holster. It was decades before I learnt that they originated with Heiser and were made by others (other than Hunter) after the 1960s. Always associated with being "cheap and cheerful" and easy to make, cheap to buy, simple to use.