chad-earthscope
commented
2 years ago The "B" value is meant to be "best" of the D,R,Q, and M qualities available as determined by the data center. Unfortunately this description is omitted from the specification and should be fixed.
As @kaestli notes this ("B" value) is not a SEED quality code and only has meaning as a value for the service parameter.
The (optional) quality parameter is allowed to take the values D, R, Q, M, B, with B as the default value (see table 1, page 2 of the standard document) For definition of the values, it refers to the SEED standard, i understand: to byte 7 of the fixed header of a data section as described in the SEED standard document v. 2.4, page 108. However, this document just describes values of D, R, Q, and M. Thus, it remains unclear what the default parameter value B means, and how the service should behave if such a value is indicated in the query string.
Side note: some current implementations of fdsn web services implement the (optional) quality request parameter, but only a subset of the parameter values specified, while answering with http 400 to other values. The dataselect WS specification is not explicit on the question whether a parameter being optional also implies that the support of each of its potential values is optional, or whether the support of the parameter, if implemented, should be complete. For a better predictability of service behaviour, i would suggest that a next version of the standard would request the latter.