1	void IDS_range_search(m_context cxt){
2	a_handle tbl = a_arg(cxt,0);   // Table handle
3	int pos = a_int_arg(cxt,1);   // Indexed pos 
4	int l = a_int_arg(cxt,2); // lower range
5	int u = a_int_arg(cxt,3); // upper range
6	IDShead *ind=(IDShead *)mexima_identifier(pos, tbl,ids_type);
7	IDScomparer cmp = mexima_get_comparer(pos, tbl, ids_type);
8	// call the map function of IDS-API: 
9	IDSmap(ind->root, l, u,
10	      (IDSmapper)rangemapper, cmp, cxt);}
       // the function rangemapper() is defined as:
11	int rangemapper(IDSitem *kv,m_context cxt){
12	a_bind(cxt, 4, kv->value);
13	a_emit(cxt);}


The IDS_range_search() accesses the first four function parameters from the binding context cxt on lines 2-5. 
Lines 2 and 4-5 dereference the handles to get integer values. 
Line 6 assigns the pointer ind to the index structure on position pos of table tbl. 
Line 7 gets a pointer to the compare function registered in the BAO table. 
On line 9 the index API IDSmap() iterates over the index ind and calls the function range-mapper(kv,cxt), defined on lines 11-13, 
on each index entry kv in the index. On line 12 the row (value part) of the key/value pair in the index is bound to the result 
(5th pa-rameter). Finally, the macro a_emit() emits a result tuple.