H.262 == MPEG-2 Part 2 Video == ISO/IEC 13818-2. Video codecs are fun because multiple standards bodies publish their own version of the same codec. The ITU-T publishes the H.26x specs, and ISO/IEC publish the other xxxxx-x specs.

Pesonally I like the ITU-T because you can get the specs for free from them. ISO/IEC demand $242 for a copy of ISO/IEC 23008-2 (also known as MPEG-H Part 2 or HEVC). But ITU-T will give you H.265's spec (which is the same codec as ISO/IEC 23008-2) for free: https://www.itu.int/rec/T-REC-H.265