With credit to David Waldmann:  
 
Get the DBA Source Code from the CD. I have copied it to a folder on my hard drive called DBA Source Code, with a shortcut to that folder on my desktop. Don't be afraid of the source code - you can't break DBA with it unless you change it, recompile it, and replace the original files in the DBAMFG folder with it.  
 
Each of the menu items in DBA runs a program which correspond to the menu name, prefixed with a "BK" and an extension of "RUN". The source code files are named the same way with the exception of the extension, which is "SRC". For instance, AP-B runs the program named bkAPB.run, so open the Source Code file named bkAPB.src.  
 
The first time you try to open one of the files you will most likely get an "Open this file with what application?" Dialog box. Select Notepad (unless you really want to use your word processor), and make sure the "always use this application for this file type?" is checked off so you don't have to go through this every time (you could also rename all the source code files with an extension of TXT if for some reason you have other SRC files you open with another application).  
 
Once the file is open scroll all the way down to the bottom. The last section will consist primarily of a table-like list of data looking something like this:  
 
\FIELDS  
BKAP.INVL.CODE   0 21  3  0  0 0   10    0    0AYRGBKAPINVLNNN    0  
BKAP.VENDNAME   0 48  3  0  0 0   30    0    0ANRGBKAPVENDNNN    0  
BKAP.INVL.NUM     0 21  4  0  0 0   10    0    0AYRGBKAPINVLNNN    0  
INV.DATE     0 48  4  0  0 0    8    0    0S RGMEMORY  NNN    0  
BKAP.INVL.TYPED  0 21  5  0  0 0   10    0    0AYRGBKAPINVLNNN    0  
BKAP.INVL.DATE    0 48  5  0  0 0    8    0    0DNRGBKAPINVLNNN    0  
 
(if the above list looks funny, make sure that the display window is wide enough to display each full line on one line)  
 
This is a list of all the information required to run the menu item. The first item is the field name, followed by a bunch of numbers that you don't need to worry about, and then the file name somewhat hidden in the middle of some other gobbledygook. In the example above I've highlighted the file names, and you can see two different files plus one called "Memory". Any field in "Memory" or "Defined" which is another one you may see occasionally are not actual fields in the file, but information that you enter on the screen, or calculated by DBA with another program.  
 
So you sometimes must link two or more files to get all the information, or you might have to make a formula to figure out some others, but most of the information is available this way.  
 
And of course the actual file name in the DBA folder has an extension. If you are using the default company the extension is just "B". If you've created a new company number 13 then the extension would be "B13", etc.  

No, the section of code Tim was displaying is for text output. The RTM's are different. You need to use the Modify Forms program to see what fields we are printing.

In most cases that RTM refs fields like BKAR_INV_NUM, or BKAR_INVL_PCODE   The tables these come from are BKARINV and BKARINVL. There is also the BKARCUST file in there too. so the tables you need to look at are BKARCUST, BKARINV, BKARINVL  
 
you can use the DBA Help to print a list of the tables and UT-H to print fields...