The description of the ToDateTime function in the Logical Specification indicates that the resulting DateTime should have time components unspecified, whereas the description of the ToDateTime function in the CQL Reference indicates that the resulting DateTime should have time components set to zero. On the grounds that the ToDateTime function in FHIRPath indicates the time components should be unspecified, the description of the operation in the reference should be corrected to indicate the time components are unspecified.

https://hl7.org/fhirpath/#datetime-conversion-functions