What do the two defaults mean in the ORDER array of a cloud search query?

I am trying to understand the logic behind the order of cloud search results.

When I do some kind of search query in my Cloudant database, I get, for example, the following result:

{"total_rows":3,
"bookmark":"g1AAAAGieJzLYWBgYMtgTmGQS0lKzi9KdUhJMtLLTMo1MLDUS87JL0",
"rows":[
  {
     "id":"a13cad998851cd8428e84388b113d972",
     "order":[
        8.46020221710205,
        494
     ],
     "fields":{
        "SLP_NOME":"CF-PL-1527-2011",
     }
  },
  {
     "id":"5a131a5eb363dc8c2f162499d9fcb810",
     "order":[
        8.449498176574707,
        483
     ],
     "fields":{
        "SLP_NOME":"CF-PL-1529-2011",
     }
  },
  {
     "id":"3bc1a4fe211305cba1e558e963327a6f",
     "order":[
        8.077779769897461,
        1967
     ],
     "fields":{
        "SLP_NOME":"CF-PL-5094-2013",
     }
  }
]}

      

        
        
        
      

    

I know that the first value is the relevance result results.rows[x].order[0]

. This is the default collation.

However, what is the meaning of the second value results.rows[x].order[1]

?

The only information I could get is:

order: Specifies the order in relation to indexed fields

https://docs.cloudant.com/api/search.html

But I didn't get it. What do they mean with "indexed value given"?

THANKS!