HQMF R2.1 defines standard population criteria types (initialPopulationCriteria, numeratorPopulationCriteria, etc). For each of there predefined population types, there is a default logical grouper. This is explained in section 4.11:

We can see from the above example, that the precondition element within an initialPopulationCriteria element does not explicitly mention any of the logical groupers "AllTrue", "AllFalse", "AtLeastOneTrue", etc. This is because the initialPopulationCriteria, numeratorCriteria, denominatorCriteria, and MeasurePopulationCriteria all have a default precondition of AllTrue within the populationCriteriaSection. Similarly NumeratorExclusionCriteria, DenominatorExclusionCriteria, DenominatorExceptionCriteria, and MeasurePopulationExlusionCriteria have a default precondition of AtLeastOneTrue.