arangosh> db._create("test"); 
[ArangoCollection 6948, "test" (type document, status loaded)]
arangosh> for (i = 0; i < 100; ++i) { db.test.save({ value: i }); }
arangosh> db.test.ensureIndex({ type: "skiplist", fields: [ "value" ] });
{ 
  "id" : "test/7252", 
  "type" : "skiplist", 
  "fields" : [ 
    "value" 
  ], 
  "unique" : false, 
  "sparse" : false, 
  "isNewlyCreated" : true, 
  "code" : 201 
}
arangosh> var explain = require("@arangodb/aql/explainer").explain;
arangosh> explain("FOR i IN test FILTER i.value > 97 SORT i.value RETURN i.value", {colors:false});
Query string:
 FOR i IN test FILTER i.value > 97 SORT i.value RETURN i.value

Execution plan:
 Id   NodeType          Est.   Comment
  1   SingletonNode        1   * ROOT
  9   IndexNode           50     - FOR i IN test   /* skiplist index scan */
  5   CalculationNode     50       - LET #3 = i.`value`   /* attribute expression */   /* collections used: i : test */
  8   ReturnNode          50       - RETURN #3

Indexes used:
 By   Type       Collection   Unique   Sparse   Selectivity   Fields        Ranges
  9   skiplist   test         false    false            n/a   [ `value` ]   (i.`value` > 97)

Optimization rules applied:
 Id   RuleName
  1   move-calculations-up
  2   move-filters-up
  3   remove-redundant-calculations
  4   remove-unnecessary-calculations
  5   move-calculations-up-2
  6   move-filters-up-2
  7   use-indexes
  8   remove-filter-covered-by-index
  9   use-index-for-sort
 10   remove-unnecessary-calculations-2