definiens: means tyrosine - derived polymers co ntaining desaminotyrosyl - tyrosine or desaminotyrosyl - tyrosine alkyl ester repeat units l inked together by carbonate backbone linkages as de scribed in subsections ( a ) through ( e ) below and which compris e a subgroup of the polymers defined by the compreh ensive chemical Formula VIII listed under CLAIM 1 in US Pa tent 6,475,477B1 . POLYCARBONATES exclude all polymers commonly referred to as Appendix C - 1 polyarylates . With reference to said Formula VIII, for the purposes of this License Agreement, a POLYCARBONATE is a polymer that meets all the follo wing conditions : a. described in said Formula VIII is limited to being a simple carbonyl group, e.g., carbon double bonded to oxygen as indicated by Structure 1 ; AND ( Structure 1 ) b. XI and X2 in said Formula VIII are independently Iodine or Bromine atoms ; Y1 and Y2 in said Formula VIII are independently 0, 1, or 2 . Non - radio - opaque poly mers are obtained if both Y1 and Y2 are equal to ze ro ( 0 ) ; AND c. R7 in said Formula VIII is independently an alky lene group containing up to 4 carbon atoms ( e.g., m ethylene, ethylene, propylene, or butylene ) ; AND d. R9 and R12 in said Formula VIII are limited by t he requirements that ( i ) R4 equals ( -CH2- ) with subscript equals 2 as defined in Claim 3 of said US patent ( ii ) R0 equals ( -CH2- ) with subscript equals 1 as defined in Claim 3 of said US patent ( iii ) Z in Claim 3 is limited to a free carboxylic acid group or carboxylic acid esters or amides havi ng straight or branched alkyl and alkyl aryl groups containing up to 18 carbon atoms, or esters and amides of biologi cally and pharmaceutically active compounds ; AND e. The parameter in said Formula VIII can vary from 0 to 0.99 ( including the values of and ) . The parameter in said Formula VIII can vary from 0 to 1 ( including the values of and ) . The par ameter in said Formula VIII is between 5 and 3,000