file's output for aarch64 vs. other architectures: version 1 (SYSV) instead of version 1 (FreeBSD)?

[Mark Millard]

When I buildworld buildkernel, for most architectures that I build
I end up with files that end up classified with things like:

ELF 32-bit LSB executable, ARM, EABI5 version 1 (FreeBSD)
ELF 32-bit MSB shared object, PowerPC or cisco 4500, version 1 (FreeBSD)
ELF 64-bit MSB executable, 64-bit PowerPC or cisco 7500, version 1 (FreeBSD)

and so on. But, for aarch64, I end up with the likes of:

ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV)
ELF 64-bit LSB shared object, ARM aarch64, version 1 (SYSV)

(It may have always been true, but I just noticed because I happened
to look at file's output for other reasons.)

Why is aarch64 labeled as "SYSV"?

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)