MOD13Q1.061 year-end Pixel DOY versus RangeEndingDate

[robbot_abchihgtsv1j]

Hello,

Could you clarify the temporal semantics of this MOD13Q1 Collection 6.1 granule?

Product: MOD13Q1.061
Granule: MOD13Q1.A2012353.h25v04.061.2021224010348.hdf
RangeBeginningDate: 2012-12-18
RangeEndingDate: 2013-01-02

In a 96x96 native-grid window, the official HDF contains Pixel DOY values 3, 5, 7, and 8 in 6,749 pixels with non-fill NDVI. Under year-end rollover, these correspond to dates from 2013-01-03 through 2013-01-08. The HDF's INPUTPOINTER includes A2013001 MOD09 inputs.

The corresponding AppEEARS output matches the official HDF exactly for Pixel DOY, NDVI, DetailedQA, and Pixel Reliability: 36,864 integer values compared, with zero mismatches. Native-grid coordinates and indexing also agree.

PCR17-021 mentions end-of-year processing and "days from next cycle":
https://modaps.modaps.eosdis.nasa.gov/cgi-bin/PCR_detail.cgi?file=/Land/PCR17-021.dat

Could you please clarify:

1. Are next-calendar-year pixel acquisition DOY values expected and valid in the final 16-day MOD13Q1 composite of a year, including this specific case?

2. Does RangeEndingDate strictly bound all source observations contributing to selected pixels, or does it describe only the nominal granule/composite temporal extent?

3. For scientific lineage and train/validation/test split-boundary handling, should pixel-level DOY be treated as the actual observation date when it extends beyond RangeEndingDate? If so, how should the calendar year be assigned?

A reference to the applicable product documentation or processing specification would be appreciated.

Thank you.