I'm not sure that you can easily create a brief definition.
Start by going to Annex A in the standard (either ISO 9001:2015 or AS9100D), A.6 Documented information. The term documents is no longer used in the standard, and A.6 shows how the new term, documented information, treats the old terms of documents and records. A.6 describes what was previously known as a document is now referred to as maintained documented information, and what was previously known as records is now known as retained documented information.
Next, look at 7.5.1 in either standard.
"The organization's quality management system shall include:
a) documented information required by this International Standard;
b) documented information determined by the organization as being necessary for the effectiveness of the quality management system."
The following list applies to ISO 9001:2015. I have not ferreted out a list of additional topics for AS9100D.
Maintain (Document)
- 4.3 Maintain DI of Scope
- 4.4.2 Maintain DI to support operation of processes
- 5.2.2a Maintain DI of Quality Policy
- 6.2.1 Maintain DI of Quality Objectives
- 8.1e1) Operation planning includes determining, maintaining, and retaining DI to the extent necessary for confidence that processes have been carried out as planned
- 8.1e2) Operation planning includes determining, maintaining, and retaining DI to the extent necessary to demonstrate conformity of products
- 8.2.4 relevant DI is amended when product requirements are changed
- 8.5.1 As applicable, availability of DI that defines characteristics of products or services to be provided that ensure production under controlled conditions
- 8.5.1 As applicable, availability of DI that defines results to be achieved to ensure production under controlled conditions
So you need to document the above topics because they are required by the standard.
Then you need to document anything that you have determined you need to document.
As far as written procedures are concerned, ISO 9001:2015 has no requirement for written procedures. AS9100D requires written procedures for control of nonconforming product and corrective actions.
There is no requirement for work instructions, standard operating procedures, or the like, UNLESS you (the organization) choose to have them, and if you do, they are fair game for auditors.
I hope this helps.