A is a five-part pattern in the shape of a wedge. Unlike in a classic , wave 4 must run into the territory of wave 1 there. Diagonals only occur in two places: leading in wave 1 and ending in wave 5 or C. Wave 3 is always a classic impulse, never a diagonal.
Leading diagonal
The leading diagonal comes at the start of a trend, in wave 1. The structure is 5-3-5-3-5 or 3-3-3-3-3. Wave 1 is usually the longest, wave 3 never the shortest, wave 5 never longer than wave 3. Waves 2 and 4 usually retrace 50–78.6%. Wave 2 of the larger trend follows.
Ending diagonal
The ending diagonal comes at the end of a move, in wave 5 or C, and consists of five three-part waves (3-3-3-3-3): waves 1, 3 and 5 must be zigzags, 2 and 4 can be anything. Wave 5 stays below 100% of wave 3; if it runs further, the assumption is wrong. With its end, the larger move is complete.
Rare – handle with care
Diagonals are rare, expanding ones especially so. Slight overshoots of the wedge lines do not count as a rule violation. On weekly candles our rule only recognizes contracting diagonals (wave 3 shorter than 1, wave 5 shorter than 3, wave 4 overlaps wave 1) and leaves out expanding ones.