It is important for you to identify quality records as you go through your documents. Ensure where records are defined within a procedure or by a system, that it exists and is controlled. I have been into a number of companies where a procedure would call out a record which at some time was eliminated. The procedure was never revised to reflect the system change.
In the simple document matrix we are using as an example (Document_Matrix_Example.xls) you can see there there are forms [blue type] (which are controlled documents) which become controlled records [red type]. The procedure calling out each record is, in this type of matrix, closely identified by sequence [procedure then form then record].
It is becoming more and more common for these to be electronic. That does not change the requirements, but many companies do not have a related matrix - they just rely on directory listings or something similar. While I have no problem not having a matrix which relates the documents (in large corporations this isn’t feasible), remember there are typically many links / relationships which, over time, tend to ‘get lost’ in complicated systems.