=== Acronyms with internal periods ===

n.a.s.a.
U.S.S.R
פ.צ.
  \_ (Hebrew F.C.)

=== Acronyms without internal periods ===

IBM.
asap
մթա (Armenian B.C.E)

=== Multi-codepoint acronyms ===

সি.ও.পি.ডি. (Bengali C.O.P.D.)
អេ.ភី. (Khmer A.P.)
બીબીસી (Gujarati BBC)
ఎంఐటి (Telugu MIT)

=== Names with intials with periods ===

J.R.R.Tolkein
Д.Р.Р. Толкин

Ю́.В.Про́хоров (Russian Yuri Prokhorov, with diacritic)
L.M̂. (French CD name, with diacritic)

=== Names with intials without periods ===

MC Escher
МК Эшер

=== Not acronyms ===

wikipedia.org
legen...dary
Ph.D
B.Sc.
1.2.3.4.
A. B. C. D.
e̪f.g (the character before f is a "non-letter" combining mark)