I am using SMOKE v2.5. In section 6.17.1 of its manual, there is a paragraph explaining the “many-step hierarchy is used in applying the temporal cross-referencing”:
“… When there are missing entries in the cross-reference file, Temporal first looks for cross-reference entries for other species at the same level in the search hierarchy before descending to the next level in the hierarchy. For example, if a source has a temporal cross-reference entry for CO but not for NOx, Temporal uses the source-specific CO temporal cross reference entry for allocating NOx from that source in preference to using a default NOx temporal profile.”
I have a question about the example. If the source has entries for CO and SO2 but not for NOx, whose (CO or SO2) entry will be used for NOx?