Certified Unix. The source link has more details:

    Apple Inc.: macOS version 14.0 Sonoma on Apple silicon-based Mac computers

    Apple Inc.: macOS version 14.0 Sonoma on Intel-based Mac computers

    IBM Corporation: z/OS 3.1 or later with: z/OS 3.1 or later Security Server and z/OS 3.1 or later C/C++ Compiler on IBM Series Processors that support z/OS Version 3.1 or later

    IBM Corporation: AIX version 7, at 7.2 TL5 (or later) on systems using CHRP system architecture with POWER™ processors

    IBM Corporation: AIX version 7, at either 7.1 TL5 (or later) or 7.2 TL2 (or later) on systems using CHRP system architecture with POWER™ processors

    Hewlett Packard Enterprise: HP-UX 11i V3 Release B.11.31 or later on HP Integrity Servers

    IBM Corporation: AIX 6 Operating System V6.1.2 with SP1 or later on Systems using CHRP system architecture with POWER™ processors and 2, 8 or 128 port async cards

    IBM Corporation: AIX 5L for POWER V5.3 dated 7-2006 or later on Systems using CHRP system architecture with POWER™processors

    IBM Corporation: z/OS V2R1 or later with: z/OS V2R1 or later Security Server and z/OS V2R1 or later C/C++ Compiler on IBM zSeries Processors that support z/OS Version 2 Release 1 or later

    The SCO Group, Inc.: UnixWare ® 7.1.3 and later for single and multiprocessor systems based on IA-32 and compatible processors and conforming to PC architecture

    The SCO Group, Inc.: SCO OpenServer Release 5 and OpenServer Release 6 on Single and Multi-processor Industry Standard Intel architecture platforms

Source: https://www.opengroup.org/openbrand/register