Chapter 22: The Message Segment, Fields, and Components (and Sub-Components)-Conditional Predicates (related to conditional optionality of segments/fields)
Chapter 49: Message Control (Segments and Fields related to message identification and processing)-Message Header Segment (MSH) - fields, especially-MSH-9 Message Type , MSH-10 Message Control ID, MSH-11 Processing ID (Production, Training, Debugging)
Chapter 51: Message Control Message Header Segment (MSH) - fields, especially-MSH-17 Country Code, MSH-18 Character Set, MSH-19 Principal Language of Message, MSH-20 Alternate Character Set Handling Scheme, MSH-21 Message Profile Identifier
Chapter 58: Given this section is also listed in the previous block, this might indicate a deeper dive into specific complex scenarios of message control, error handling related to control, or advanced uses of fields within MSH, SFT, UAC.
Chapter 66: Local Extensions ("Z- Notation")-Rules for creating locally defined HL7 tables (user-defined tables), Implications of local extensions on interoperability and conformance
Chapter 73: Coded Element Data Types ID (Identifier - Coded Value from HL7 or External Table), IS (Identifier - Coded Value from User-defined Table), CE (Coded Element), CWE (Coded With Exceptions), CNE (Coded With No Exceptions),
Chapter 74: Identifier Data Types PT (Processing Type), CX (Extended Composite ID with Check Digit), CK (Composite ID with Check Digit - deprecated), EI (Entity Identifier), EIP (Entity Identifier Pair), PL (Person Location)
Chapter 87: Conformance-Conformance Constructs/Mechanisms-Usage (R - Required, RE - Required but may be Empty, O - Optional, C - Conditional, X - Not Supported, W - Withdrawn)