| http://www.w3.org/ns/prov#value | - divalent group selected from the following formulas containing aromatic rings: ##STR3## wherein R1, R2, R3 and R4 which may be identical or different represent each a hydrogen atom, an alkyl group having 1-4 carbon atoms or an alkoxy group having 1-4 carbon atoms, provided that R1, R2, R3 and R4 are not hydrogen atoms at the same time: ##STR4## wherein R is an alkylene group having 1 to 10 carbon
|
