File Object Variable
When a file is to opened, read or modified in stages and then closed, the file system associates these actions with a "stream" that can identified in future actions by a file object. The user must create a unique file object variable for each open file, though the variable can be reused once a file has been closed.
You can create a file object variable with built in data styles FILEASC or FILEBIN.

  VAR( name, 0, FILEASC ); // name is a file object variable with data read/write as ASCII
  VAR( name, 0, FILEBIN ); // name is a file object variable with data read/write as binary (raw)

You can also create your own file styles to alter the way data bytes are read/written. The encode property determines how this data is managed. Refer to the data styles for the VAR() command for the options. The predefined styles are:

  STYLE( FILEASC, data ) { type=file; encode=sr; } // This will store a varU8 = 12 as two bytes \\31\\32
  STYLE( FILEBIN, data ) { type=file; encode=sd; } // This will store a varU8 = 12 as one byte \\0C

The visibility property can be checked to see if the file object variable is currently assigned to a file stream. An assigned variable is "visible", and unassigned variable is not "visible".

  CALC( res, varFileObj, "EVIS" ); // res is 1 if varFileObj is in use. 

The error strings in FILERES0 to FILERES19 are variables of type TXT and have a maximum length of 32 characters. They can be accessed and changed, as any other text variable. For example:
  LOAD( FILERES4, "File was not found!" ); // Change default "File Not Found" message
  TEXT( txtName, FILERES1 );; // Display the Disk Error message on the screen

Maximum simultaneous open files - v49.19
Increased maximum simultaneous open files to 8 (this includes menu files, images, as well as those opened with FILE() command).

File Tests - v49.32
Tests added to check filename length when reading/writing to NAND. Note maximum length is 15 characters.

Potential Future Commands - Not Yet Supported
These commands are not implemented but could be made available in future development depending on customer demand.
FILE( "DIR", [fileRes], dst, [format], pathName ); // Formatted directory listing
FILE( "APPENDLN", [fileRes], fileObj, fileName, [numWritten], data [, data [, ...]] ); // Open, Append Line, Close File (given fileName)
FILE( "READLN", [fileRes], fileObj, [numRead], data [, numToRead] ); // Read Line (given open fileObj)
FILE( "STATUS", [fileRes], fileName ); // Get File Status
FILE( "WRITELN", [fileRes], fileObj, [numWritten], data [, data [, ...]] ); // Write Line (given open fileObj)
FILE( "WRITELN", [fileRes], fileObj, fileName, [numWritten], data [, data [, ...]] ); // Open, Write Line, Close File (given fileName) 

  FILE( "DATE", varRes, varTxt, "d M Y H:i:s", "NAND/tree.bmp" );
  FILE( "DATE", , varTxt, "Y", varSrcName );