Source: constant.js

/**
 * Values used throughout Canadarm to keep logs consistent.
 *
 * @namespace constant
 * @memberof Canadarm
 * @property UNKNOWN_LOG {string} - Constant for unknown log values.
 * @example
 *   logAttributes = {values: someStuff, unkownValue: Canadarm.constant.UKNOWN_LOG};
 * @readonly
 * @static
 * @final
 */
Canadarm.constant.UNKNOWN_LOG = '?';