Attributes associated with the object to which a link points may be retrieved using the -a option to the vls command. Attributes associated with the link itself may be retrieved using the -A option to vls. Attributes may be set using the set_atr command.
Attributes in Prospero have three different value types: SEQUENCE, FILTER, LINK. They can be in one of three namespaces: APPLICATION, FIELD, and INTRINSIC. They have five different precedences: OBJECT, ADDITIONAL, REPLACEMENT, CACHED, and LINK. The FILTER type, in turn, has a number of options. These are all discussed in depth in the Prospero protocol manual. A link or object may have multiple instances of any attribute on it. This array of specialized features makes set_atr appear confusing at first.