परादिश्छन्दसि बहुलम्

The first syllable of the second member is diversely acutely accented (उदात्त) in the छन्दस् (Vedas).
Karika

परादिश्च परान्तश्च पूर्वान्तश्चापि दृश्यते ।
पूर्वादयश्च दृश्यन्ते व्यत्ययो बहुलं ततः ॥

The word पर "the second member" refers to सक्थ, as well as to any other word in general. Thus अञ्चिसक्थ꣡मालभेत, but लोमश꣡सक्थः so also ऋजुबाहुः, वाक्पतिः, चित्पति ॥ In the non-Vedic literative these last two compounds will be final acute by 6.1.223, rule 6.2.18 not applying because of the prohibition contained in 6.2.19.

The rule is rather too restricted. It ought to be: "In the Veda, the first syllable and the final syllable of the second member, as well as the final syllable and the first syllable of the preceding member are seen to have the acute accent, in supersession of all the foregoing rules".

As to where the final of the second terms takes the acute, we have this Vartika- In the Veda, त्रिचक्र &c have acute on the final of the second term. As त्रिचक्रेण, त्रिबन्धुरेण, त्रिवृतारथेन ॥ नियेन॑ मुष्टिष्ठत्यया॑ ॥

As to where the final of the preceding takes the acute, we have this Vartika:- The words मरुद्वृद्ध &c in the Vedas have acute on the final of the first term. As मरु꣡द्वृद्धः and विश्वा꣡युः ॥

As to where the first syllable of the preceding takes the acute, we have this Vartika:- In the Veda, the words दिवोदास &c have acute on the first syllable of the first member. As दिवोदासाय सामगाय ते ॥