[djsumdog]

I have never seen it. Is it often used in legal text?

[selllikesybok]

It's more like a class signifier. People who have certain educational backgrounds, or read a lot of certain types of writing, are more likely to use it.

[travmatt]

Like the semi-colon; useful for showing you went to college.

[mark212]

no, not really. The most common latinism is "ibid" in its various forms, which is used to avoid repeating a full citation.

NB is used more like "i.e." or "e.g." in the US, from my experience.

[dboreham]

Everyone in the UK would know what it means. I doubt it is particularly common in legal documents. Probably something to do with having a decent proportion (>0.001%) of the population educated in the classics...