Xkb allows applications to obtain information about indicators using two different methods. The first method, which is similar to the core X implementation, uses a mask to specify the indicators. The second method, which is more suitable for applications concerned with interoperability, uses indicator names. The correspondence between the indicator name and the bit position in masks is as follows: one of the parameters returned from XkbGetNamedIndicators is an index that is the bit position to use in any function call that requires a mask of indicator bits, as well as the indicator's index into the XkbIndicatorRec array of indicator maps.
XkbGetIndicatorMap obtains the maps from the server for only those indicators specified by the which mask and copies the values into the keyboard description specified by desc. If the indicators field of the desc parameter is NULL, XkbGetIndicatorMap allocates and initializes it.