Human body weight refers “to a person's mass or weight. Body weight is measured in kilograms … or pounds. Strictly speaking, body weight is the measurement of weight without items located on the person. Practically though, body weight is measured with clothes on, but without shoes or heavy accessories such as mobile phones and wallets and using manual or digital weighing scales. Excess or reduced body weight is regarded as an indicator of determining a person's health, with body volume measurement providing an extra dimension by calculating the distribution of body weight.” – Wikipedia. This class represents the measurement (or “clinical observation”) of the patient’s Weight. This class re-defines the generic clinical Observation class to fix the observed characteristic to LOINC 3141-9 and to set the data type of the observation value to a Physical Quantity. "Weight (in pounds).... Decimal precision is permissible." - PCORnet Common Data Model, Vital.WT