Functions concerning input and output from and to file. 
| Name | Description | 
| Append | Open a file in append mode | 
| Assign | Assign a name to a file | 
| Blockread | Read data from a file into memory | 
| Blockwrite | Write data from memory to a file | 
| Close | Close a file | 
| Eof | Check for end of file | 
| Eoln | Check for end of line | 
| Erase | Delete  file from disk | 
| Filepos | Position in file | 
| Filesize | Size of file | 
| Flush | Write file buffers to disk | 
| IOresult | Return result of last file IO operation | 
| Read | Read from file into variable | 
| Readln | Read from file into variable and goto next line | 
| Rename | Rename file on disk | 
| Reset | Open file for reading | 
| Rewrite | Open file for writing | 
| Seek | Set file position | 
| SeekEof | Set file position to end of file | 
| SeekEoln | Set file position to end of line | 
| SetTextBuf | Set size of file buffer | 
| Truncate | Truncate the file at position | 
| Write | Write variable to file | 
| WriteLn | Write variable to file and append newline |