In the following table, the available syntax of the tag names is summarized.
| Tag | Meaning | Address range (decimal) | 
| SM (91h) | Special relay, 1-bit value | 0000 to 2047 | 
| SD (A9h) | Special register, 16-bit value | 0000 to 2047 | 
| X (9Ch) | Input, 1-bit value | 0000 to 8191 | 
| Y (9Dh) | Output, 1-bit value | 0000 to 8191 | 
| M (90h) | Internal relay, 1-bit value | 0000 to 8191 | 
| L (92h) | Latch relay, 1-bit value | 0000 to 8191 | 
| F (93h) | Annunciator, 1-bit value | 0000 to 2047 | 
| V (94h) | Edge relay, 1-bit value | 0000 to 2047 | 
| B (A0h) | Link relay, 1-bit value | 0000 to 8191 | 
| D (A8h) | Data register, 16-bit value, unsigned | 000000 to 012287 | 
| W (B4h) | Link register, 16-bit value, unsigned | 0000 to 8191 | 
| TS/TC (C1h)/(C0h) | Contact/Coil timer, 1-bit value | 0000 to 2047 | 
| TN (C2h) | Current value timer, 16-bit value, unsigned | 0000 to 2047 | 
| SS/SC (C7h)/(C6h) | Contact/Coil retentive timer, 1-bit value | 0000 to 2047 | 
| SN (C8h) | Current value retentive timer, 16-bit value, unsigned. | 0000 to 2047 | 
| CS/CC (C4h)/(C3h) | Contact/Coil counter, 1-bit value | 0000 to 1023 | 
| CN (C3h) | Current value counter, 16-bit value, unsigned. | 0000 to 1023 | 
| SW (B5h) | Link special register, 16-bit value, unsigned. | 0000 to 2047 | 
| SB (A1h) | Link special relay, 1-bit value | 0000 to 2047 | 
| DX (A2h) | Direct input, 1-bit value | 0000 to 8191 | 
| DY (A3h) | Direct output, 1-bit value | 0000 to 8191 | 
| R (AFH) | File register – Block switching method, 16-bit value | 
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| Z (CCH) | Index register, 16-bit value | 
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| ZR (B0H) | File register – Serial number access method, 16-bit value | 
 | 
Our implementation of MELSEC protocol also supports the following extension tags:
| Tag | Meaning | Address range (decimal) | 
| DS (A8h) | Data register, 16-bit value, signed | 000000 to 012287 | 
| DD (A8h) | Data register, 32-bit value, signed | 000000 to 012286 Use regular D registers, | 
| FL (A8h) | Data register, 32-bit float value | 000000 to 012286 Use regular D registers, address increased by 2 | 
| WS (B4h) | Link register, 32-bit signed value | 0000 to 8191 Use | 
All custom tags consist of multiple regular 16-bit tags in the least to the most significant word order.