INCOMPLETE THREAD INCOMPLETE THREAD A threaded profile having either crests or roots, or both crests and roots not fully formed, resulting from the intersection with the cylindrical or end surface of the work or the vanish cone. It may occur at either end of the thread. INDEPENDENT FAILURE A failure that occurs without being caused by or related to the failure of associated items, distinguished from dependent failure. INDEXING HOLES Indexing holes are holes placed in a printed- board blank to enable accurate positioning for processing. (Index- ing holes may or may not be on the finished board.) INDEXING NOTCH An indexing notch is a notch placed in the edge of a printed board blank to enable accurate positioning for processing. (Indexing notches may or may not be on the finished board.) INDEX LIST (IL) A tabulation of data lists and subordinate index lists pertaining to the item to which the index applies. INDICATOR-LIGHT HOUSING An electrical device that accommodates a lamp, both electrically and mechanically, and pro-