a) the vector triplet <x,y,z> refer <height, index, parent_index>
b) blocks, block100, block110 (of height 1) are mined together and they both refer previous block block00[null] (of height 0).
Block, block110 (of height 1) gets a child block and its branch grows but
block block100 doesn't get any child block till then and became leaf/fork.
Please advise what happens to the ith transaction t100i of block, block100 that is not included in the branching block, block110.