CHAIN_START
for (nodep = CHAIN_START(mdp->node_list); nodep != NULL; ) {
for (propp = CHAIN_START(nodep->prop_list); propp != NULL; ) {
for (msp = CHAIN_START(mdp->string_list); msp != NULL;
for (mdbp = CHAIN_START(mdp->data_block_list); mdbp != NULL;
for (nodep = CHAIN_START(mdp->node_list); nodep != NULL;
for (nodep = CHAIN_START(mdp->node_list); nodep != NULL;
for (propp = CHAIN_START(nodep->prop_list); propp != NULL;
for (msp = CHAIN_START(mdp->string_list); msp != NULL;
for (mdbp = CHAIN_START(mdp->data_block_list); mdbp != NULL;
for ((_itv) = CHAIN_START(_chain); (_itv) != NULL; \