Use TDD consistently

[mmccool]

"Directory" is a generic term, we should use TDD consistently to refer to the Thing Description Directory service.

[farshidtz]

Is there a case where we need to refer to directories in general within the specification? TDD is too wordy.

[mmccool]

still needs to be done, but editorial, can do during REC

[mmccool]

In general, use of "directory" (lower case) is probably ok, and not worth re-opening the REC to change at this point. Let's revisit this terminology however for the next version. Will change the label so it's still open, but for Discovery 1.1.