What are the headers used in kernels in old version CTS?

For some reason, I am running a pretty old version of CTS on a machine, the last commit was from 2021. More precisely, it was the commit at 5281b4c916bd7ab540dd9c1c7a199a7dba52165f. In that version of conformance test suite code, there are some c++ style include statements involving header files I never heard of. For example, in the clcpp/api/test_spec_const.hpp file:

const char * kernel_test_spec_consts_defaults =
    "#include <opencl_memory>\n"
    "#include <opencl_work_item>\n"
    "#include <opencl_spec_constant>\n"
    "using namespace cl;\n"

What are these files opencl_memory, opencl_work_item and opencl_spec_constant? I have looked into the whole directory, and didn’t find the files named these. Are they implicitly included in the cl compiler or something? Why are they not used anymore in the current CTS?