References

1. Specifications

DMTF DSP0134: System Management BIOS (SMBIOS) Reference Specification. Defines the entry points, the structures of the standard types and their fields, which OpenDMI decodes up to version 3.10.
DMTF DSP0270: Redfish Host Interface Specification. Defines the protocol records of the management controller host interface structures.
DMTF DSP0266: Redfish Specification. Defines the format of the dates and times firmware inventory structures carry.
Intelligent Platform Management Interface (IPMI) Specification: Defines the interfaces of the baseboard management controllers IPMI device structures describe.
Intel® RSD Firmware Extension Specification Software v2.3.2: Document 337201-003US. Defines the structures of Intel Rack Scale Design platforms.

Structures some vendors define have no public specification, and their layouts come from the software of the vendors which reads them:

Dell libsmbios: Structures of Dell platforms.
illumos: Structures of Sun platforms, as defined in usr/src/uts/common/sys/smbios_impl.h.

Where it is known, the source of the layout of a vendor-specific structure is given along with it in the specifications part of this manual.

dmidecode: Reference tool for reading DMI/SMBIOS data on Linux and other systems. Dump files are interchangeable between dmidecode and OpenDMI.