repeat barline with four dots

A barline with four dots indicates repetition, just like a regular one with two dots. It's common in hymnals and choral works, indicating a section repeated with the same notes but different lyrics.
The four-dotted repeat can also indicate a section that should be repeated many many times, like the fade-out ending of Holst's Neptune. Holst uses both the two-dot and four-dot repeats to mean different things, which indicates they aren't just a colloquialism of engraving style, they are semantically distinct.

attaching three examples