The "Unknown:"s below indicate that an entry is incomplete.

• either the entry exist in the language, and please tell.
• either the entry doesn't exist in the language, and please tell so. The entry will be marked as such and won't appear as missing anymore.

• Various

  { ... }	block (grouping statements, especially when statements are not expressions)
  #	commenting (until end of line)

• Control Flow

  b	breaking control flow (goto (unconditional jump))
  t label	if_then
  ;	sequence
  end-of-line	sequence

• Strings

  s/.{n}(.).*/\1/	accessing n-th character
  s/.{n}(.{len}).*/\1/	extract a substring
  p or i	simple print (on strings)
  \U / \L / \C	upper / lower case character

• Bags and Lists

  /elt/

  is an element in the list