simple tag:
  no extra whitespace           value1
  whitespace after open delim   value1
  whitespace before close delim value1
  whitespace after command      value1

tag pair:
  no extra whitespace             value1
  open tag:
    whitespace after open delim   value1
    whitespace before close delim value1
    whitespace after command      value1
  close tag:
    whitespace after open delim   value1
    whitespace before close delim value1