Clause 7.1.2 is the specified substance level. The published edition builds a second set of identifiers from the specified substance rather than from the parent substance. The specified substance is the form named in the authorisation and used in the product: the salt, the hydrate, the solvate or another modification that changes the strength or the behaviour of the product. The clause is placed within the strata description, so its rules are about which elements make up the level and how the level relates to the substance level. The exact assignment rules are not in the public preview and are not stated in the text we hold. The public FDA material describes the specified substance stratum as running through the same four levels as the substance stratum, with the specified substance replacing the substance as the starting element.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.