The verb kī is substituted for the verb cāyṛ 'to worship, to observe', when the Intensive affix yaṅ follows.,
The phrase यङि is understood here. Thus चेकीयते, चेकीयेते, चेकीयन्ते ॥ The exhibition of की in the sutra with a long ई indicates that there is long vowel even in tenses where यङ् is elided, as चेकीतः ॥ For if the sutra had enunciated कि with a short इ as the substitute of चाय्, the forms चेकीयते &c would have been still valid. Thus कि + यङ् = चि + कि + य = चे + कि + य = चे + की + य 7.4.25 causing the lengthening of the short इ). But then the Nishtha would have been चेकितः which is wrong.,