#include <libBM.h>

Up can be longer than Down. Down must be fully present in Up (TODO optional) See chart:
 
| Public Member Functions | |
| datalink () | |
| Constructor. | |
| datalink (const RV &rv, const RV &rv_up) | |
| void | set_connection (const RV &rv, const RV &rv_up) | 
| set connection, rv must be fully present in rv_up | |
| vec | pushdown (const vec &val_up) | 
| Get val for myself from val of "Up". | |
| void | pushup (vec &val_up, const vec &val) | 
| Fill val of "Up" by my pieces. | |
| Protected Attributes | |
| int | downsize | 
| Remember how long val should be. | |
| int | upsize | 
| Remember how long val of "Up" should be. | |
| ivec | v2v_up | 
| val-to-val link, indeces of the upper val | |
 1.5.6
 1.5.6