You can see what information Dimensions pulls out for the BACS Export by opening the BacsFormats.xml with a text editor such as Notepad. This file is located within the Extras folder of the Dimensions installation folder, which is usually in:
C:\Program Files (x86)\Access Applications\Dimensions\Accounts\<Your Dimensions Version>\Extras
You can then press CTRL + F to bring up the search bar, where you can search for the BACS format you're trying to create, for instance BACS Standard 18.
There are usually around 9 lines on a BACS export, but that can vary. Anything between <Line> and </Line> is all the data that's pulled through onto one horizontal line of the BACS export.
So for the following:
<Format Name="BACS Standard 18" Number="25" FileFormat="Fixed">
<Header>
<Line>
<Number>1</Number>
<Field>
<Number>1</Number>
<Content>VOL1</Content>
<DecimalPlaces>0</DecimalPlaces>
</Field>
<Field>
<Number>2</Number>
<Content>[SubmissionSerialNumber]</Content>
<Length>6</Length>
<Justify>Right</Justify>
<PadCharacter>0</PadCharacter>
<DecimalPlaces>0</DecimalPlaces>
</Field>
<Field>
<Number>3</Number>
<Content>[PaymentListName]</Content>
<Position>42</Position>
<Length>6</Length>
<Justify>Left</Justify>
<PadCharacter>space</PadCharacter>
<DecimalPlaces>0</DecimalPlaces>
</Field>
<Field>
<Number>4</Number>
<Content>1</Content>
<Position>80</Position>
<DecimalPlaces>0</DecimalPlaces>
</Field>
</Line>
It will show something similar to this on the first line of the BACS export file:
VOL1000011 141 1
The text in square brackets [ ] is the information the BACS format is gathering onto the BACS export. So this
<Content>[PaymentListName]</Content>
Means it's bringing in the Payment List name, if it exists on the transaction.
The rest of the file is laid out in a similar way, so you can go through this file to see what sort of information the BACS format is using, and where it's getting it from.