The glossary is a definition of terms within the private operating rules. This includes defining entities who are affected by the rules, including participants (direct, and in some cases, indirect), operators, processors, third parties, etc.
As an example, here is a link to the L1P Glossary. Please note, this glossary is not intended to represent the comprehensive list of terms that an operating rules glossary would need to cover.

Glossary Example

Adjacencies: Ways in which businesses, banks or other financial services providers realize revenue from services that are not directly associated with payments—for example, loans made to payments account holders.
Agent: An authorized person or entity that handles financial account opening and/or transactions on behalf of another entity. The other entity may be a bank or, in some countries, a non-bank provider of digital financial services. Cash-in, cash-out (CICO) is a common service provided by agents.
Authentication: The mechanism whereby systems may securely identify their users. Authentication systems provide answers to the questions: Who is the user? Is the user really who he/she represents themselves to be? In payments systems, signatures and PINs are common methods of authentication.
Authorization: The permission given by the paying person or entity to make the payment. In a push payment, the paying person authorizes their bank or financial service provider to make a payment. In a pull payment (such as a card payment), the paying person’s bank or financial service provider answers the payee’s question: “Is the payer authorized to make this payment?” Note that authorization means a good funds guaranty in some systems (such as card systems), but not in others (such as direct debits).
Automated Clearing House (ACH): Electronic bank transfer systems which operate in most countries. ACH’s handle either or both credit push or debit pull (also called direct debit) payments. ACHs operate by having most banks in the country belong to the ACH: either directly or through intermediary banks. The ACH switch moves transactions from one bank to another, and either provides for, or interfaces with, a net settlement system.
Bank Transfer Systems: Open-loop payment systems used by banks in a country. Checking, ACH, wire transfer, and some card systems are all bank transfer systems. In some countries, these systems are being opened up to non-bank participants.
Batch Processing: An approach through which transactions are held together in a batch and then processed at the same time. In financial services, transactions may be batched together and processed at different intervals, e.g., every few hours, or at the end of the day. Batch processing contrasts to real time processing.

The Financial Inclusion Perspective

A glossary helps to provide transparency and clarity to all players participating in the scheme, helping to level the playing field.