Programs use the MS-DOS national-language-support (NLS) functions to retrieve and set country information, such as the time format, the currency symbol, and the screen and printer code pages.
Following are the MS-DOS NLS-related functions:
| Function | Description | Version |
| 38h | Get/Set Country Information | 2.0 |
| 6501h | Get Extended Country Information | 3.3 |
| 6502h | Get Uppercase Table | 3.3 |
| 6504h | Get Filename Uppercase Table | 3.3 |
| 6505h | Get Filename-Character Table | 3.3 |
| 6506h | Get Collate-Sequence Table | 3.3 |
| 6507h | Get Double-Byte Character Set | 3.3 |
| 6520h | Convert Character | 3.3 |
| 6521h | Convert String | 3.3 |
| 6522h | Convert ASCIIZ String | 3.3 |
| 6601h | Get Global Code Page | 3.3 |
| 6602h | Set Global Code Page | 3.3 |