1. Rule 17 provides a peremptory 10-day period for entering appearance to defend, calculated from the day after service, regardless of whether summons is served alone or with a declaration. 2. The proviso to Rule 119 extends only the time for filing a plea, exception or special plea (to 20 days total from service) when summons and declaration are served simultaneously under Rule 113 - it does not extend the dies induciae for entering appearance to defend. 3. Under Rule 449(1)(a), rescission is available only where the court made an error - a party's own mistaken interpretation of procedural rules does not constitute an erroneous grant of judgment. 4. An applicant under Rule 449 must prove the error or mistake relied upon; there is no need to establish 'good and sufficient cause' as required under Rule 63.