Here is some code that will process your string container into lines of records that you want but you might want to change a few things to get this working with your records after converting your string container to a simple csv file you can then map it to your record mapper and process it any how.

Class TestEnvironment.Custom.GENERAL.ContainerString Extends (%Persistent, %Populate, %XML.Adaptor, %ZEN.DataModel.Adaptor)
{

Property Mystring As %String(MAXLEN = 32000, XMLPROJECTION = "CONTENT");

ClassMethod Import()
{
    // Create an instance of %XML.Reader
    Set reader = ##class(%XML.Reader).%New()

    // Begin processing of the file
    Set status = reader.OpenFile("C:\TEST\test.xml")
    If $$$ISERR(status) {do $System.Status.DisplayError(status)}

    // Associate a class name with the XML element name
    Do reader.Correlate("StringValue","TestEnvironment.Custom.GENERAL.ContainerString")
    
    // Read objects from xml file
    While (reader.Next(.object,.status)) {
	    
	   
        Write object.Mystring,!
        
//check the length of the string
         set lstr=$length(object.Mystring,",")
	    write "The length of incoming string is : "_lstr
	    if (lstr>28)
	    {
//divide by 28 for your processing
		    set div=lstr/28
		    if (div=2)
		    {
//assign your strings to something and write to file to map your records
			    set newstrObject=$piece(object.Mystring,",",1,28)
			    set secNewStrOJect=$piece(object.Mystring,",",29,56)
			 }
			 elseif (div=3)
		    {
			    set newstrObject=$piece(object.Mystring,",",1,28)
			    set secNewStrOJect=$piece(object.Mystring,",",29,56)
			     set thirdNewStrOJect=$piece(object.Mystring,",",57,84)
			     
			     write "this is the string cut1 :"_newstrObject,!
			      write "this is the string cut2 :"_secNewStrOJect,!
			       write "this is the string cut3 :"_thirdNewStrOJect,!
			 
		 }}
    }
    
    // If error found during processing, show it
    If $$$ISERR(status) {do $System.Status.DisplayError(status)}
}


}

hope this helps

This will do exactly what you want any problems give us shout

ClassMethod ImpCSV(fileName As %String = "C:\filepath where csv file is")
{
	;;Refresh globals data at the begin of proecess
	;;globals hold the file being written to data and the count of lines each file has 
	k ^ufile,^ufile2,^counter,^counter2
	set Reader =##class(%Stream.FileCharacter).%New() 
	
	;;link to the file to read	 
	set status=Reader.LinkToFile(fileName)
		
   if $$$ISERR(status)
	{
		do $System.Status.DisplayError(status)
	}
	;;initialise the counter for the file lines to write to one file	 
	set ^counter =0
	set ^counter2 =0	
	set ^ufile=""
	set ^ufile2=""
    
    ;;the count for the lines read in
	set lineCount=0
	;;start process the lines
	while 'Reader.AtEnd
	{
		;;read the incoming file
		set line=Reader.ReadLine()
		;;increment the line count by one as you read the next line
		set lineCount=lineCount+1		
	
	    ;;piece the column to check
	    ;;one is for the first column and so on
	    ;;string at after the equal sign is the value to check for 
		if ($piece(line,",",1)="Religion")
		{
			;;increment count for this file
			 set ^counter=^counter+1
			  ;;the counter is at one to assign the file path to write to
			   if (^counter=1)
				{
					;;set the file name to write to the global
					set ^ufile=..writeFileOut("fileone",".csv",line,,^counter)
				}
				else
				{
					;;check the count has no reached the limit for the number of lines to write to
					if (^counter=51)
					{
						;;reset the count if limit reach
						set ^counter=1
					    ;;new file
					    set ^ufile =..writeFileOut("fileone",".csv",line,,^counter)
					    }
					    else
					    {
						    ;;use the current file
						    do ..writeFileOut(,,line,,^counter,"REG")
						 }
					}			
		  }
		  ;;second check for the next set of data if you have more than 
		  ;;two to check for copy the below and change accordingly to accommodate the next check
		  ;;same as above
		  if ($piece(line,",",1)="description")
		  {
			  ;;set attributes for the second file to write to
			   set ^counter2=^counter2+1
			   if (^counter2=1)
			   {
					set ^ufile2=..writeFileOut("fileTwo",".csv",line,,^counter2)
				}else
				{
					if (^counter2=51)
					{
						set ^counter2=1
						;;new file
						set ^ufile2= ..writeFileOut("fileTwo",".csv",line,,^counter2)
					}else
					{
						do ..writeFileOut(,,line,,^counter2,"DESC")
					}
				}				 			
	}
		  
}

 kill ^ufile,^ufile2
}

ClassMethod writeFileOut(filename, fileext As %String, line As %String, directory = "C:\directory to store files", linecount As %Integer, FileToUse)
{
	set oLF = ##class(%Library.File).%New()
	if (linecount=1)
	{
		
	    Set filenam=directory_filename_$i(^timmmy)_fileext
	    set oLF.Name=filenam
	    if (oLF.Open("wns"))
	    {
		    set linecount=linecount+1
		    do oLF.WriteLine(line)
		    do oLF.Close()
		    ;;w oLF.Name
		    quit oLF.Name	
	   }
	}else
	{
		if (FileToUse="DESC")
		{
		     if (^ufile2'="")
		     {
		         set oLF.Name=^ufile2
			}
		}elseif(FileToUse="REG")
		{
		     if (^ufile'="")
			 {
			     set oLF.Name=^ufile
			  }
		}
	    If (##class(%File).Exists(oLF.Name))
	     {
		     
		     Do oLF.Open("EWA")
		     if (linecount'=51)
		     {
			     set linecount=linecount+1
		         do oLF.WriteLine(line)
		         do oLF.Close()
		          quit oLF.Name
		     }
		 }
	}
}