The PDBX_LIGSCREEN_INVESTIGATION_LIB_COMPONENT_MIX category provides a mechanism to assign distinct combinations from the screened
Chemical Library or Series compounds (n=>1) a unique singular identifier. This is particularly useful when each experiment involves the
target being exposed to a mixture of compounds, as occurs on occasion with fragment screening libraries. Individual ligands
or fragments in this category are referred to via their id as defined in the PDBX_LIGSCREEN_INVESTIGATION_LIB_COMPONENT category.