Thank you for your question regarding CMS1218v1, Hospital Harm - Postoperative Respiratory Failure. For this measure, an inpatient hospitalization period includes time in outpatient surgery service or observation when the transition between discharge from these encounters, if they exist, and admission to the inpatient encounter is one hour or less. The logic filters out inpatient encounters immediately preceded by an emergency department visit so that only inpatient encounters preceded by outpatient surgery service or observation if they exist are assessed. The "Elective Inpatient Encounter with OR Procedure within 3 Days" logic definition, used to identify the measure's Initial Population criteria, uses the "HospitalizationWithObservationAndOutpatientSurgeryService" function to identify the appropriate inpatient hospitalization period for assessment. This function returns the total interval from the start of any immediately prior emergency department visit, outpatient surgery service, or observation visit to the discharge of the inpatient encounter, when the transition period between the end of these encounters and the start of the inpatient encounter is one hour or less. However, a separate definition also used to identify the measure’s Initial Population criteria, "Elective Inpatient Encounter with Age 18 and Older without ED Visit," then filters out any inpatient encounters preceded by an emergency department visit that ends one hour or less before the start of the inpatient encounter. Please see the highlighted logic in the attached screenshot that shows how these encounters are filtered out. We will consider logic changes for improved clarity in a future update.