code: function Pattern(value, parameters) {
      abstractions.Element.call(this, utilities.types.PATTERN, parameters);
      value = value || '^none$';  // the default value matches nothing
      if (typeof value === 'string') value = new RegExp(value);
  
      // since this element is immutable the value must be read-only
      this.getValue = function() { return value; };
  
      return this;
  }
docs: PUBLIC CONSTRUCTOR 
  This constructor creates a new pattern element using the specified value.
  
  @constructor
  @param {String|RegExp} value A regular expression for the pattern element.
  @param {Parameters} parameters Optional parameters used to parameterize this element.
  @returns {Pattern} The new pattern element.