A dynamic is a symbol which, when placed on a staff, affects the loudness of notes that follow it. Technically, the term that describes the notes' affected property is "velocity".
The dynamic edit dialog Edit
To place a dynamic on a staff in Harmony Assistant, choose the wanted dynamic from the dynamics tools and place it in the desired point on a staff. For graphical reasons, if you place a dynamic vertically close to a previous one, the dynamic will snap to the same vertical position. After placing the dynamic on the staff, Alt+double click on it to bring the dynamic edit dialog. Depending on which type of dynamic you selected, the dialog will take different forms.
The first type of dynamics edit dialog applies to immediate dynamics (like p, f, ff, mf etc.). It consists of a range of dynamic options.
Firstly, there's the dynamic list. Changing the dynamic type from this list doesn't also change its power.
Below, there is a power slider. Note that the values this can take range from 0% to 500%. This happens because dynamics do not directly affect a note's velocity value - which could range from 0 to 127. Instead, it applies a percent to the notes' personal velocity, which results in a different final velocity. At a mf value (100%), all notes output their own velocity, which can be defined by altering each note separately, or by using parameter curves. Both velocities before and after the dynamic alteration are visible in parameter curve edit mode.
A text box allows you to denote a caption for the dynamic. This will be displayed instead of the dynamic symbol. To use a f, p, m or z symbol, write $f, $p, $m or $z respectively. To use the original symbol of the dynamic, insert $x.
The next options are "Played", which enables or disables the dynamic. If the dynamic is played, a cumulative option is present. When a dynamic is cumulative, during repetitions, the dynamic's value multiplies with itself for the second, third or nth time. It is also possible to apply the dynamic to all staves on the score, or just to the merged staves (in other words all voices of the current staff, it is a multi-voice one). The following checkbox shows or hides the dynamic.
At the bottom of the dialog there is a list of repetitions. When a break renders a dynamic as repeating, this can apply either to all repetitions, or only the ones selected here.
The dialog used for gradual dynamic changes (crescendos and decrescendos) is just slightly different from the first one, through that instead of a dynamic type controller and one strength slider, it has two strength sliders, one for the beginning of the dynamic and one for the end of it. The velocities are gradually morphed over the dynamic length (which is established by its graphical location and size). When the starting value is larger than the ending value, the dynamic is changed to a decrescendo. Otherwise, it becomes a crescendo.
The tempo is considered in the program as being in fact a dynamic, and so are the octave and pedal symbols.