APL was designed in the 1960s as an array-based programming language by Kenneth Iverson, and has evolved and added many new features over the intervening decades. It was first standardized in 1989, before the latest, extended, standard was published in 2001. This talk will present how Dyalog’s flavour of APL conforms to the latest standard, some differences to the versions of APL implemented by other vendors, and places where Dyalog APL diverges from the standard, along with Dyalog’s rationale for doing so.