Shared Parameters Pay
Shared parameters are the bridge between QTO's results and native Revit. QTO can add a fixed
group of Revit shared parameters — AEC-Codes_QTO — to your model, so the lengths, areas, volumes,
counts and catalog codes it computes live in real parameters you can schedule, tag, filter and colour by.
Why they matter
QTO always stores its results in the document's internal storage (Extensible Storage) — that is what QTOReport and QTOExport read. Shared parameters are different: they put the same numbers into the model itself, with correct units, so you can drive native Revit schedules, tags, view filters and colour overrides from them — and they travel with the file to anyone who opens it, no add-in required to read them.
The parameters
The group AEC-Codes_QTO uses stable GUIDs, so the same parameters are recognised
across every project and survive a reload, and native data types, so quantities carry the
right units.
Quantities — mapped in QTOMappings and filled by QTOCompute:
AEC_QTO_Length,AEC_QTO_Width,AEC_QTO_Height,AEC_QTO_Thickness— lengthAEC_QTO_Area— area;AEC_QTO_Volume— volumeAEC_QTO_Weight— number;AEC_QTO_Count— integer
Classification & grouping (text): AEC_QTO_Zone, AEC_QTO_Phase and AEC_QTO_Size — used as grouping keys when you build the bill of quantities.
Catalog tag: AEC_QTO_CatalogCodes (the assigned price-list code or codes) and AEC_QTO_ItemCount (how many catalog items are on the element).
Price-list provenance (text): AEC_QTO_PricelistVersion and AEC_QTO_PricelistHash record which price list and version a tag came from.
Add-in data & diagnostics: AEC_QTO_Payload (a multi-line mirror of the element's full assignment — written and read by QTO, not meant to be edited by hand) and AEC_QTO_Flags (diagnostic notes written by QTOCompute).
Creating them
QTO adds the group from QTOSetup → Create Shared Parameters, binding it to the model categories QTO supports (around 40, across architecture, structure, MEP and site). A matching action removes the binding again. Because the GUIDs are fixed, re-running the command is safe: parameters that already exist are detected and left in place.