The I/O point labels of every node on the network (digital inputs, digital outputs, analog inputs and analog outputs together) share one fixed IoUserLabelBufferBytes (65536) byte buffer in controller memory. Each stored label costs its own characters plus 7 bytes of bookkeeping. When a label does not fit, nothing is stored and an RsiError reports how many bytes the label needed and how many were available, so you can shorten labels or label fewer points. The node's own label (UserLabelSet) has its own storage and does not come out of this budget.
1.15.0