When saying simply "until" it includes or excludes what mentioned after it?
For example:
You should make registration until Monday.
"It's best to avoid full-body bathing until the second day after surgery"
When saying simply "until" it includes or excludes what mentioned after it?
For example:
You should make registration until Monday.
"It's best to avoid full-body bathing until the second day after surgery"
Your examples are different, as the second one is a negative, but it is clear from
It's best to avoid full-body bathing until the second day after surgery.
that "until" means you can bathe from the second day. In which case this will mean the same
It's best to avoid full-body bathing before the second day after surgery.
The first case is more tricky
You should make registration until Monday.
I would assume this means that registration on Monday is allowed, if not then I would write
You should make registration before Monday.
So whether until is inclusive or not, depends on the context.
The second one first:
"It's best to avoid full-body bathing until the second day after surgery"
This means you can start bathing on the second day.
The first one is problematic.
You should make registration until Monday.
This one doesn't work, any way you slice it.
For starters, I wouldn't say 'make registration'. Just use the verb 'register'.
Also, 'until' doesn't work in this case, because the act of registering is a one-time thing. So I think you should go with either 'by' or 'no later than' instead:
You should register by/no later than Monday.
Or better yet:
The registration deadline is Monday.