nl_tokens: Creates a new Index instance .
pl_tokens: function Index ( name , target , kind , options ) { /**
     * Name of the index.
     * @type {String}
     */ this . name = name ; /**
     * Target of the index.
     * @type {String}
     */ this . target = target ; /**
     * A numeric value representing index kind (0: custom, 1: keys, 2: composite);
     * @type {Number}
     */ this . kind = typeof <mask> === 'string' ? getKindByName ( kind ) : kind ; /**
     * An associative array containing the index options
     * @type {Object}
     */ this . options = options ; }