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if /^(([A-Za-z][A-Za-z0-9]*)(\.([A-Za-z][A-Za-z0-9]*))*)(\s|,|=)/ { ... $hashref->{$1}=""; } }
DB1.UK, DB2.UK = ( ... (CONNECT_DATA = (SID = db5)) )
DB1.UK DB3.UK DB5.UK.US