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@@ -143,6 +143,29 @@ and count is how many instances of this spec can be created. A
 complete value for this variable could be: \fB4096,102400,2=225
 2560,102400,2=20 512,102400,2=21\fR.
 
+.TP
+.I KM_USED_CPU, KM_USED_MEM, KM_USED_DSK
+These represents the metrics of used resources at the start of the
+computation (only for tiered allocation mode).
+
+.TP
+.I KM_POOL_CPU, KM_POOL_MEM, KM_POOL_DSK
+These represents the total resources allocated during the tiered
+allocation process. In effect, they represent how much is readily
+available for allocation.
+
+.TP
+.I KM_UNAV_CPU, KM_UNAV_MEM, KM_UNAV_DSK
+These represents the resources left over (either free as in
+unallocable or allocable on their own) after the tiered allocation has
+been completed. They represent better the actual unallocable
+resources, because some other resource has been exhausted. For
+example, the cluster might still have 100GiB disk free, but with no
+memory left for instances, we cannot allocate another instance, so in
+effect the disk space is unallocable. Note that the CPUs here
+represent instance virtual CPUs, and in case the \fI--max-cpu\fR
+option hasn't been specified this will be -1.
+
 .TP
 .I ALLOC_USAGE
 The current usage represented as initial number of instances divided