The simple case: A node is completely allocated. On Noctua 2, for example, a node has 128 CPU cores. These are multiplied by the runtime of the job and result in the CPU core h of the job.
The slightly more complicated case: 1 CPU but 50% of the available RAM has been allocated. In this case, the node is considered to be 50% utilized. We convert the utilization of the ram into CPU equivalents. 50% of the ram means 64 CPU equivalents for Noctua 2. These are then used as the basis for the CPU core h calculation, even if only one CPU has been allocated.
The calculation can be described more generally as follows: The CPU equivalents of the RAM used are calculated. The maximum of the allocated CPU cores and the CPU equivalents of the working memory are then taken and multiplied by the runtime of the job.