ðiːz wɜː fˈɔːɹmɚli kˈʌvɚd ɪn dɪstˈɪŋkt spˌɛsɪfɪkˈeɪʃənz, bˌʌt æz ʌv pˌiːsˌiːˈaɪ ɛkspɹˈɛs fˈaɪv.zˈiəɹoʊ hɐvbɪn mˈuːvd tə ðə pˌiːsˌiːˈaɪ ɛkspɹˈɛs bˈeɪs spˌɛsɪfɪkˈeɪʃən.
These were formerly covered in distinct specifications, but as of PCI Express 5.0 have been moved to the PCI Express Base Specification.