What colored ink should be used for what purpose?

[ParagS Kulkarni]

Is there any convention to use certain colored ink should be used for certain purpose. e.g. Black pen for something, Red for something, Green for something else.

[fred rosenberger]

In the U.S., many legal documents are supposed to be signed in blue ink. That way, it's easy to tell if something is an original or a photocopy (at least, before color copies became common).

WHY this makes a difference is unknown, but the court likes to have originals and the various lawyers and parties all get copies.

[Paul Clapham]

You may well have heard the term "red ink" referring to debt. That's an old accounting convention -- black for credits, red for debits -- but that hasn't really applied for years and now that computers do the accounting, it's history.

[Pat Farrell]

fred rosenberger wrote:In the U.S., many legal documents are supposed to be signed in blue ink. That way, it's easy to tell if something is an original or a photocopy (at least, before color copies became common). WHY this makes a difference is unknown

Because for a lot of scanners, blue is one of the colors that drop out. So a scanned copy of the document does not show the signature.

Most mono-chrome scanners and copiers have very strong differences in their ability to pick up some colors.

The use of "drop-out" color inks are common in business forms that are processed in high volume imaging applications, such as the US Census.

[Pat Farrell]

Paul Clapham wrote:You may well have heard the term "red ink" referring to debt. That's an old accounting convention -- black for credits, red for debits -- but that hasn't really applied for years and now that computers do the accounting, it's history.

Not fully history.

Even Excel can show negative values in Red, its a Format -> Cell option.

Its a standard within the accounting reporting world (at least in the US) and makes it easy to see when a project or division is not popular.