They have a net version now. Here is a code sample they sent me. I believe they provide a set of custom controls for text entry etc that tie directly to their data. I purchased codebase about 2 years ago and then found that I was not able to use it. They honored the 60 day money back guarantee without any questions.

using System ;
using CodeBase ;

namespace c4ap
{
class ex58
{
[STAThread]
static void Main(string[] args)
{
Code4 cb = new Code4() ;
Data4 data = new Data4( cb, "INFO" ) ;
Tag4 firstTag = new Tag4() ;
firstTag.initFirst( data ) ;

data.select( firstTag ) ; //select the first tag of the first opened index

int count = 0 ;
for( data.top( ); data.eof( ) == 0 ; data.skip( 1 ) )
{
Console.Write( "position in the tag: " + ++count ) ;
Console.WriteLine( " Record Position: " + data.recNo( ) ) ;
}
cb.initUndo( ) ;
}
}
}