Multi-dose vial
A multi-dose vial is a container designed to be entered more than once, usually because its contents include a preservative.
The design assumption is repeated entry through a rubber stopper that reseals. Guidance on these containers concentrates on what happens around them — how they are entered, what enters them, and what gets reused.
A record of which container a given entry came from, and when, is the part of this a log can actually contribute. It cannot observe technique or certify that anything was done correctly.
What it is not
Multi-dose does not mean indefinite use, and it does not mean the contents cannot be contaminated. The preservative limits bacterial growth; it does not sterilise anything introduced into the container.