Block-Wise Construction of Trimagic Squares with Bimagic Blocks of Order 9 (17496)

A fixed bimagic square of order nine and its entrywise complement are combined with trimagic outer squares by a balanced complementary product. The resulting complete squares are normal trimagic, although each aligned 9x9 block is bimagic and non-trimagic. We provide a periodic sign arrangement, a full moment proof and the exact progression of distinct ordinary block constants. The retained computation records nine complete orders from 108 to 17496, arranged in three multiplication-by-nine chains. A newly regenerated order-108 example independently checks the construction, while larger exported matrices are described from their earlier verification records. The distinction between the infinite constructive implication and the finite numerical inventory is maintained throughout. Text files of complete work are attached