“Permission to copy, modify and distribute the files collectively known as the System Reference Document 2024 (“SRD2024”) is granted solely through the use of the Open Gaming License, Version 1.1.”
If WotC puts that statement (taken and modified from the 5.1 SRD) at the top of the SRD, and assuming the 1.1 OGL only allows forward compatibility, it’s clear the 1.0a OGL is not an authorized version for this SRD.
See above. This wouldn’t be the first time a new license is not compatible with an older version (e.g., GNU GPL v2 and v3 are
not compatible unless the former is licensed as v2+).