Statistically distributed structural collections

The standard structure database assumes that the chemical structure is fully resolved. That is true for most of the small molecules in the pharmaceutical industry. But for example in the cosmetic industry statistical distributions of molecule segments like PEG are quite frequent. In the formulation example above you find the examples of Polysorbate 20 and PEG 600. While PEG 600 is already described in the “Polymer” section above, Polysorbate 20 is defined by the condition: w + x + y + z = 16 meaning that the polymer brackets identify 16 PEGs but the total number per side chain is not given, instead the distribution over the 4 potential location is defined by the total amount of units

 
The Sgroup data element “16” in the drawing above presents the rule w + x + y + z = 16. Because the Sgroup data are searchable other Polysorbates differing in the total number of units may be registered into a database as well.
General remark: if you have to work with statistical distribution in chemical structures you have to ensure unique drawing rules and support the drawing by structure templates that can be easily modified by the personal involved. In doubt let an administrator take the decision to identify the correct drawing.