By convention, music is divided into groups of beats that we call "measures."  Each measure may have its own key signature, meter, and measure number.  Measure numbers appear at the top of the Clips View and other views:

Vertical lines in the view separate measures.  A heavier line in the view is used to show a meter change.  "Tic" marks between measure numbers show metronome beats.  In the above picture, the meter changes from 2/4 time to 6/8 time at bar 13.

If you are sufficiently "zoomed out," there may not be enough space to show all measure numbers.  In this case, some numbers are omitted:

In the above picture, tic marks between measure numbers are used to show the position of intervening measures.

What is a Key Signature?

A key signature is a group of sharps or flats printed on the staffs at the beginning of a piece of music to show the key in which it is to be played.  Position the song at the measure where the change is to occur, then use the Insert/Key Signature command:

There are fifteen possible key signatures, ranging from seven flats to seven sharps.  If you've selected a range of time, the "from measure" and "through measure" will be set automatically to reflect this selection.  Otherwise, the "from measure" initially will be set to the current measure, and the "through measure" initially will be set to the measure where the next key change occurs, or the end of the song, whichever occurs first.

What is a measure's Meter?

A measure's meter determines the size of the measure, and how it's divided into "beats."  You may also specify the number of metronome clicks in the measure, if this is to be different from the number of beats.  Position the song at the measure where the change is to occur, then use the Insert/Meter command:

You may select almost any number of beats per measure, but the "beat value" must be one of 1, 2, 4, 8, 16, or 32.  These numbers correspond to whole notes, half notes, quarter notes, eighth notes, sixteenth notes, and thirty-second notes, respectively.  You will notice that in the preview window, according to musical notation convention, "common time" (4/4) is drawn as a "C" and "cut time" (2/2) is drawn as a "C" with a vertical line.

As with Key Signature changes, if you've selected a range of time, the "from measure" and "through measure" will be set automatically to reflect this selection.  Otherwise, the "from measure" initially will be set to the current measure, and the "through measure" initially will be set to the measure where the next meter change occurs, or the end of the song, whichever occurs first.

There are three "method" choices available here.  The first method only changes the sizes of existing measures in the measure range.  That is, if the total number of measures in the song changes as a result of this meter change, new measures will be added, or existing measures will be removed only from the end of the song.

The next two method choices preserve measure positions that follow the "through" measure.  That is, if you've chosen to change the meter of three measures from 3/4 to 3/8, six measures will take their place.  If you make a change that does not work out to an even number of new measures, one measure will contain the "odd" or remainder beats.

The difference between the last two methods has to do with the handling of measure numbers.  In the last method, if measures are added or removed in the middle of the song, measure numbers following the "through" time will remain as they were before the meter change--new measures will be assigned letters.

Can I override default measure numbers?

Measures always have numbers associated with them.  Typically, these numbers start at "1" and go to "2" then "3" etc.  However, you will find many scores with missing numbers, or "extra" numbers, typically denoted by letters or numbers followed by letters.  Such numbering results when measure numbers are "set" and then changes are made later by the composer or an arranger.

Frustratingly, the majority of music software has no method for compensating for this not-so-uncommon scenario.  MIDI Maestro, however, allows you to assign any arbitrary number/letter combination to each measure.  Use the Insert/Measure Numbers command to open this window:

You specify two values.  First, the desired measure number for the current measure, and then the total number of measures to change.  You are also given the choice of overwriting existing numbers, or inserting new numbers by sliding the existing ones over.

First, I play in a rock band and was looking for a nice Midi
sequencer that can be use to play live jam/gig and also have FULL
control over the midi. Having a Start button, with TAP for tempo, and
also playing the introduction until I decide to start the song was a
most. Other sequencer I found did'nt give you the control like
MidiMaestro does.--Steve Hollingsworth