Within the Chord Sheet of Band-in-a-Box®, Part Markers are placed to indicate a new part of the song (they typically occur every 8 bars, but you can place them at the beginning of any bar).

But what else to Part Markers do?

Change the substyle: each original Band-in-a-Box® Style includes 2 substyles: "a" and "b" - there are also MultiStyles available, typically with 4 substyles - but there can be up to 24 ("a" through "x")!
From the Band-in-a-Box® Help file:
Each style has "a" and "b" substyles. Band-in-a-Box® Multistyles also have "c" and "d" substyles, and could have from "a" to "x" for a total of up to twenty-four.

Most of these MultiStyles that we’ve made have 4 substyles, conforming to the following pop song format:
Substyle "a" is usually used for the verse of a song.
Substyle "b" is usually used for the "b-section" or the chorus, and for soloing in the middle choruses.
Substyle "c" is usually used for the intro or for an opening verse or pre-verse.
Substyle "d" is usually used for a break or interlude.

There is always a part marker at bar 1 so that Band-in-a-Box® knows which substyle to begin with. The song continues to play in one substyle until it encounters a new part marker. The substyle will change automatically on second choruses when the "Vary Style in Middle Choruses" song setting is selected.

Drum Fills: a 1-bar drum fill will occur on the bar preceeding the part marker: if you add a part marker to bar 8, the drum fill will occur within bar 7.

Section Paragraphs: adding a part marker to your Band-in-a-Box® song will move that section to a new line within the lead sheet, making it easlier to see - this is optional, and can be adjusted within the Display Options window.

How many part markers do you typically add to your Band-in-a-Box® songs?

This is very educational.

With newer versions of BIAB, it is possible to turn off the drum fill at a part marker. This increases the versatility.

Also, it’s good you mention that a few styles have more two sub styles. This may not be well known, and it’s a great tool.

Multistyles are really effective to build pro arrangements.
But be aware that they are not interpreted in RealBand as multistyles, what a pity.
It has been requested to add this feature in RealBand for several years now.

I honestly had no idea you could set a whooping 24 different types of part markers (if my understanding of the above is accurate)

I've only seen a handful of styles with more than the standard a & b markers, with 4 being the highest number and nearly all being midi-only styles at that, for some reason
And I've never seen my part markings cycle between anything above the standard a & b, so a "how to" video that shows how to do more on any given style would be quite useful.

p.s. This rather begs the question, why are there still so few styles on offer that utilise this to conform to the common forenamed convention of four substyles? This should be the standard by now (I'm aware of the 'BBox got started by jazzists'), not the rarest of exceptions!

Icelander, this was ‘a thing’ quite a few years ago. I think there was an initial push of multistyles.

Although I’ve never done it, I believe you can roll your own. If I’m remembering this correctly, one could create different sub styles with different sound-compatible RealTracks or even just different choices of drum kit in a single RealDrum. Then you save your style under a new name.

About 2010-11, according to the creation date of the Multistyles folder within the RT Demos. Sounds about right, now that you mention it, but my ponder was rather why it seems to have stopped there
Ah, that whole "not working on Mac" rears its ugly head yet again. We still can't rework styles and save as another. No wonder then that I never tried pursue this any further at the time..
But then again, 2011 was also well before I became an active forum member to speak of (if at all), let alone a regular tester for the program. This may well be worth revisiting now

Yep... part markers are very cool indeed.

As far as how many I use..... only the amount I need to use.

And they are really handy for visually marking parts of the song and adding extra measures.

I generally only use styles that have 2 styles.... the normal blue and green ones. For my style of writing they are normally sufficient and with my DAW, I can make edits as needed to add interesting things.

A simple function of part markers is to place a double bar line in the printed song. That alone makes BIAB part markers useful.

Could you please expand on this? I'm not quite sure what you mean by "double bar line," but it sounds intriguing!

You can google ‘double bar line’ to see how this looks in printed music notation. Standard stuff, to have a double bar line at the start of sections of a song. You don’t see it in BIAB on the Chordsheet View (you see the blue and green markers). Make sense?

Thanks for pointing this out - you're absolutely right!

I have BIAB Ultrapak 2018 for Windows.

With regard to the part maker, twice recently i have been able to get parts C and D to appear with consecutive mouse clicks, but when I finish the song and generate the tracks, parts C and D disappear and things revert to A and B as the norm.

I have been unsuccessful in finding any written help in the manual to describe how to set and maintain parts C and D.

Can anyone point me in the right direction?

Bunyip, what Style are you using in your song?
Someone here might be able to verify / check.

Thanks to Callie for the educational reminder about Part Markers. Certainly I use them for all the purposes outlined.

I believe one of the most important features outlined by Callie is

This feature is extremely useful for creating readable leadsheets, a subject I am a bit passionate about, as you can tell from my recent post on 'Notation Problems'. These days you often come across tunes where the sections are not necessarily of 8 bars length. I often encounter AABA tunes where the 'A' section is 10 bars. Thus, you want one line on a leadsheet which only contains 2 bars. This is handled well by the part market when using the 'Print' Notation button. However the part market does not do the same thing when using the Leadsheet Window (AltW) green button. Here, you have to fill in the Lead Sheet Options box saying exactly how many bars you want on every line. This is extremely time consuming and you have to know about this quirk. I simply do not understand why the part marker method would not be a better!

Also it is very difficult to get a Tag ending to go down onto a separate line.

In answer to Callie's question "How many part markers do you typically add to your Band-in-a-Box® songs?":

The most common song form is a thirty two bar AABA tune with each of the 'Section Paragraphs' being 8 bars. Add an extra part marker for a four-bar Intro, and one for the Tag Ending. So, most often one uses 6 part markers.

Unfortunately, many modern pop tunes do not follow this 'section paragraph' convention and you often need part markers to create 4, 3, 2 and 1 bars on a line. Of course, many published sheet music copies do not bother with the starting a new 'section paragraph' on a new line but I much prefer the common Fake Sheet method of producing leadsheets, as outlined in my previous post: http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=457880#Post457880

Callie, I put your 'section paragraph' description in inverted commas because I have not previously heard it called that. I think it is a good description but BIAB normally calls simply a 'Section', as in 'Bar-Based Section Letters'.