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The OBD-II protocol (SAE J1979) has a couple of PID's that relate to engine load:

+------+-----+---------------------------------+
| Mode | PID | Description                     |
+------+-----+---------------------------------+
|  01  |  04 | Calculated engine load value    |
+------+-----+---------------------------------+
|  01  |  43 | Absolute engine load value      |
+------+-----+---------------------------------+

I can see that calculated engine load is expected to be a number between 0 and 100%, while absolute load ranges between 0 and 25,700%.

Conceptually, what is the difference between these two fields?