mmsg — mblaze
    message argument syntax
This document outlines the message syntax used by many of the
    utilities in the
    mblaze(7)
    message system.
In general, you can always specify a filename as a message, if it
    contains a ‘/’ character. (Use
    ‘./’ to prefix messages in the current
    directory.) You can also specify a maildir folder, which will be expanded to
    all messages in the cur/ directory.
Ranges have the format
    ‘start:stop’,
    where start and stop are
    one-based indexes into the sequence. Negative numbers count from the end. If
    start is the empty string, 1
    will be used instead. If stop is the empty string,
    -1 will be used instead. Thus,
    ‘:’ represents the whole sequence. If
    the range does not contain a ‘:’, it
    is considered to be a single message, equivalent to the range
    ‘start:start’
    of size one. The special notation
    ‘start:+n’,
    selects start and the next n
    messages.
If the sequence is threaded, the following syntax may be used:
    ‘msg=’ refers to
    the whole thread that contains msg.
    ‘msg^’ refers to
    the parent of the message msg and may be repeated to
    refer to grandparents.
    ‘msg_’ refers to
    the subthread headed by msg (i.e. all messages below
    msg, with more indentation).
The following special shortcuts may be used:
  - ‘-’
- refers to the message read directly from the standard input.
- ‘.’
- refers to the current message. Additionally, the syntax
      ‘.+N’ and
      ‘.-N’ can be
      used to refer to messages relative to the current message.
- ‘+’
- refers to the next message (like
      ‘.+1’)
- ‘.-’
- refers to the previous message (like
      ‘.-1’)
- ‘$’
- refers to the last message (like
      ‘-1’)
- ‘^’
- refers to the current parent message (like
      ‘.^’)
- ‘=’
- refers to the current thread (like
      ‘.=’)
- ‘_’
- refers to the current subthread (like
      ‘._’)