Crescendo symbols are started in **dynam spines as less-than signs (<), and decrescendo symbols are started as greater-than signs (>). In **dynam spines, these marks must be terminated by the square bracket symbols "[" and "]", respectively. In addition, the marks "(" and ")" are used to indicate that either a crescendo or decrescendo is currently active, so they should occur in the data between the starting and ending markers of a (de)crescendo.
The autodynam program takes data containing only the starting marks of (de)crescendos and automatically fills in the ending and intermediate portions of the complete (de)crescendo mark. Here is an example which takes an input with only starting symbols, and fills in the complete wedge information:
Note that the (de)crescendo symbol is terminated on the data line immediately preceding the next non-null token in the **dynam spine. This is necessary to avoid crossing bar lines at the ends of (de)crescendos.
If the (de)crescendo symbol is started with <X or >X, then the X indicates that the wedge symbol is interpreted from a "cresc." or "decresc." word. The hum2muse program can be used to render the graphical interpretation of this format properly.
A dash can be inserted after the cresc./decresc. mark by adding a layout directive immediately before the start of the symbol:
(De)crescendos on a single noteIf a (de)crescendo is immediately followed by another dynamic object, the ending part of the symbol will be placed in the same token as the start of the symbol:
(De)crescendo symbols which are not intended to be printed, such as extra markings needed to generate more accurate performances of in MIDI conversions of Humdrum data are sometimes needed. These can be indicated by appending "yy" to the marking in a similar manner to the "X" mark.