The penultimate of krama is optionally lengthened before the affix ktvā when it is without the augment iṭ,
Thus क्रन्त्वा or क्रान्त्वा; but क्रमित्वा only, with इट् augment. But when क्त्वा is replaced by ल्यप्, the rule does not apply: as प्रक्रम्य, उपक्रम्य ॥ This is on the maxim अन्तरङ्गानपि विधीन् बहिरङ्गोल्यप् बाधते \a bahiranga substitution of ल्यप्' supersedes even antaranga rule\.,