Open Action Encoding

Action in the response to an open or create request describes the action taken as a result of the request. It has the following format:

bits:

1111 11
    5432 1098 7654 3210
    Lrrr rrrr rrrr rrOO

where:

L - Lock (single user total file lock status).
    0 -- file opened by another user (or mode not supported by server).
    1 -- file is opened only by this user at the present time.

r - reserved (must be zero).

O - Open (action taken on Open).
    1 - The file existed and was opened.
    2 - The file did not exist but was created.
    3 - The file existed and was truncated.