The name of a document starts with the following parts separated by "-":

domain
This is the domain where the document belongs to. In most of the cases it is the name of the DTD. Otherwise the domain is "MSR".
document class
The document class as defined in 3.1.1. Classes of documents
topic
This optional part shows the topic within the domain. E.g. in "msrsw-tr-paco", "paco" is the topic (as a shortcut for "document overview")
language
The optional language of the document. ISO 639, 2-character code e.g. "en"(english) or de(german)
state
The optional release state of the document as defined in 3.1.2. State of documents
date
The optional release date of the document.
distribution kit
The optional format of the document as defined in 3.1.3. Distribution of Documents, e.g. pdf, html

Examples are:
MSRSYS-TR-FHT: <MSRSYS DTD, Technical Report, Formatter for HTML> MSR-TR-XML: <MSR, Technical Report, XML strategy>