Binary format for array in COPY-command

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/9.5/static/datatype-bit.html
Description:

Hi, 
I could not find description of arrays for 9.6 Postgres:
https://www.postgresql.org/docs/9.6/static/sql-copy.html

Array fields have different format than all other data. They have it's own
header - and i want to know field description.

I added hardcode support of smallint[] into this module:
https://github.com/altaurog/pgcopy
And need full description to create full support of arrays.