Most database management systems (DBMS) are case-insensitive and do not require either upper- or lowercase notation. Some DBMSs, however, are case sensitive concerning entity names, and some case-insensitive DBMSs automatically change lowercase entity names to uppercase.

The PMDB uses the following notation:

• Tag names and attributes are written in lowercase.
• Attribute values are written in uppercase.
• Database entities are written in uppercase.