O'Sullivan & Hilliard's The Law of Contract (2018 8 ed). p 15.
• If the purpose of the principle is to allow B to rely on A’s apparent intent, it has been suggested that it should be necessary to show that B has relied in some way: see Atiyah (1986a). English law has generally not explicitly required this (although see The Hannah Blumenthal (1983)) and it is submitted that its stance is correct. In the commercial world particularly, it is extremely important that A knows if, at what moment and on what terms they become legally bound. Accordingly, it is undesirable for A to have to keep B’s actions under review in order to be able to spot if and when B has relied, and so tell if, when and on what terms a contract has been formed with.
The lone comma after if fazes me.
I'm guessing that the sentence means: 'It's important that A knows if + he becomes legally bound + at what moment and on what terms'. Yet this still sounds wrong; at what moment and on what terms sound too vague to conclude a sentence.