īje 'nu-yajñaṁ vidhinā
agni-hotrādi-lakṣaṇaiḥ
prākṛtair vaikṛtair yajñair
dravya-jñāna-kriyeśvaram
īje - he worshiped; anu-yajñam - with each kind of sacrifice; vidhinā - by the proper regulations; agni-hotra - by offering oblations into the sacred fire; ādi - and so on; lakṣaṇaiḥ - characterized; prākṛtaiḥ - unmodified, completely specified by śruti injunctions; vaikṛtaiḥ - modified, adjusted according to the indications of other sources; yajñaiḥ - with sacrifices; dravya - of the sacrificial paraphernalia; jñāna - of the knowledge of mantras; kriyā - and of the rituals; īśvaram - the Lord.
There are numerous kinds of Vedic fire sacrifice, each of which involves several elaborate rituals. The Brāhmaṇa portion of the Vedic śruti specifies the complete step-by-step procedure of only a few prototype sacrifices, such as the Jyotiṣṭoma and Darśa-pūrṇamāsa. These are called the prākṛta, or original, yajñas; the details of other yajñas must be extrapolated from the patterns of these prākṛta injunctions according to the strict rules of the Mīmāṁsā-śāstra. Since other yajñas are thus known by derivation from the prototype sacrifices, they are called vaikṛta, or “changed.”