Every volume is assigned use and mount attributes through an entry in the VATLSTxx member at IPL, a MOUNT command, or by the system in response to a DD statement.

The relationships between use and mount attributes are complex, but logical. The kinds of devices available in an installation, the kinds of data sets that will reside on a volume, and the kinds of uses the data sets will be put to, all have a bearing on the attributes assigned to a volume. Generally, the operating system establishes and treats volume attributes as outlined in the following sections.