- Device address and Endpoint number are decimal numbers with leading zeroes
- or 3 and 2 positions, correspondingly.
-- URB Status. This field makes no sense for submissions, but is present
- to help scripts with parsing. In error case, it contains the error code.
- In case of a setup packet, it contains a Setup Tag. If scripts read a number
- in this field, they proceed to read Data Length. Otherwise, they read
- the setup packet before reading the Data Length.
+ Device address and Endpoint number are 3-digit and 2-digit (respectively)
+ decimal numbers, with leading zeroes.
+- URB Status. In most cases, this field contains a number, sometimes negative,
+ which represents a "status" field of the URB. This field makes no sense for
+ submissions, but is present anyway to help scripts with parsing. When an
+ error occurs, the field contains the error code. In case of a submission of
+ a Control packet, this field contains a Setup Tag instead of an error code.
+ It is easy to tell whether the Setup Tag is present because it is never a
+ number. Thus if scripts find a number in this field, they proceed to read
+ Data Length. If they find something else, like a letter, they read the setup
+ packet before reading the Data Length.