Pink, blue, and white sheet

In psychiatry files, one usually comes across scenarios where it is dictated that patient was pink sheeted or blue sheeted! What exactly is the principle behind this pink sheet or blue sheet or white sheet?  I searched the web and came across Eric Tadehara's blog where he had described this in his own jocular way. The gist of which is, in case of a pink sheeted patient, the admission is involuntary and the form is filled out by doctor or any other medical professional and they are placed in residential setting for a specified number of hours.  The only difference between pink and blue is that blue sheet is filled by a law enforcement officer and white sheet is for commitment hearing and filed so that patient may be held until seen in court.