555*DBMS_PIPE.RECEIVE_MESSAGE(CHR(99)||CHR(99)||CHR(99),31.516)

Short interpretation:

• CHR(99) = 'c', so CHR(99)||CHR(99)||CHR(99) = 'ccc'.
• You’re calling DBMS_PIPE.RECEIVE_MESSAGE on the pipe named "ccc" with a timeout of 31.516 seconds.

What it does:

• The call waits up to 31.516 seconds for a message to arrive on the pipe named "ccc".
• If a message is available within the timeout, the message is returned (via the out parameter, depending on the exact overload you use).
• If no message arrives in time, you get a timeout indication (the message may be NULL and a status/return code indicates timeout).

Example usage (one common form):

• If the overload is (p_pipe, p_timeout, p_message, p_status): DECLARE v_msg VARCHAR2(32767); v_stat PLS_INTEGER; BEGIN DBMS_PIPE.RECEIVE_MESSAGE('ccc', 31.516, v_msg, v_stat); DBMS_OUTPUT.PUT_LINE('status='||v_stat||' message='||NVL(v_msg,'')); END;

Notes:

• The leading "555*" in your snippet isn’t part of the PL/SQL call; it’s likely just a formatting/marking artifact.
• DBMS_PIPE is a legacy IPC mechanism in Oracle; for new work consider using Advanced Queuing (AQ) or other IPC mechanisms.