Many of them just indicate the type of object being transformed (T_OBJECT, T_POSE, T_CURSOR) thus repeating what is indicated in t->options.
Because they don't describe what they do, many areas in the code are confusing making exceptions for the object type.
For example:
if (t->flag & (T_OBJECT | T_TEXTURE | T_POSE)) {
float obsizemat[3][3];
/* Reorient the size mat to fit the oriented object. */
mul_m3_m3m3(obsizemat, tmat, td->axismtx);
/* print_m3("obsizemat", obsizemat); */
TransMat3ToSize(obsizemat, td->axismtx, fsize);
/* print_v3("fsize", fsize); */
}