No standard, it's common for companies to make up their own (ridiculous) metrics defined however they want.
At the end of the day it's just something that the board have defined and decided to use, and if they mess up the collection then it's embarrassing for them, they lose credibility, and investors will sell or install a new board.
Even for things that have (more) precise definitions like profit or earnings, how does one know that the numbers are not deliberately or accidentally incorrect? You just have to trust the board, accountants, and auditors to do their job, and if you don't you shouldn't own the stock.
At the end of the day it's just something that the board have defined and decided to use, and if they mess up the collection then it's embarrassing for them, they lose credibility, and investors will sell or install a new board.
Even for things that have (more) precise definitions like profit or earnings, how does one know that the numbers are not deliberately or accidentally incorrect? You just have to trust the board, accountants, and auditors to do their job, and if you don't you shouldn't own the stock.