What is meant by commencement of audit?

The term ‘commencement of audit’ is important
because audit has to be completed within a given time
frame in reference to this date of commencement.
Commencement of audit means the later of the following:
a) the date on which the records/accounts called
for by the audit authorities are made available
to them, or
b) the actual institution of audit at the place of
business of the taxpayer.