WITSML- Catalog of Value Constrainted Types. Defines qualifiers for type of flow. Indicates product characteristics that were allocated back to a well as opposed to being measured at the well. Indicates product characteristics that were determined by an allowable or other performance limit. This includes allowables which are usually established by a regulatory agency for a product. Indicates product volumes that were actually measured at the port. Indicates product volumes that were derived directly from one or more other flows. A performance requirement as determined by a budget. An estimated or calculated performance, possibly based on comparable product flow units, but not based on reservoir simulations for the particular product flow unit. An amount, set by some authority, which may or may not be based on technical criteria. An estimated performance based on a simulation that includes the particular product flow unit.