Casting my mind back many years, Type 1, 2, 3 and 4 doors were types of fire resisting doors refered to in old British Standard Codes of Practice - eg CP3: Chapter IV: Part 1: 1971 - which was Precautions against Fire in Flats and Maisonettes. Never heard of a Type 5 though.
The standard is way out of date as it talks about 25mm (1 inch) door stops and no mention of intumescent strips or smoke seals.
From memory of the locations where the doors were used Type 1 was the highest clasification, Type 2 were used onto stairs, Type 3 were internal flat doors and Type 4 were cross corridor smoke doors.
CP3 was the code of practice referred to by the Building Regulations 1985 under the Mandatory rules for means of escape in case of fire.
This code was basically superceeded when 5588 pt1 was expanded from covering single dwellings to also include flats in 1990.
Hope this helps,
Dave.