I have a rather basic question, in relation to the MCD43A4 006 NDVI dataset in GEE. 
I am aware of the methods used for the generation of the BRDF MODIS dataset, but I would like to know more details about the NDVI product. 
Does this products in GEE include only high quality observations? How can I check its specifications (e.g. quality, method of generation)
in GEE? The only information that I see in GEE is the following : 
  
 

     The Normalized Difference Vegetation Index is
    generated from the Near-IR and Red bands of each scene as (NIR - Red) /
    (NIR + Red), and ranges in value from -1.0 to 1.0. This product is generated from the MODIS/006/MCD43A4 surface reflectance composites.



Thanks for any advice.