Since I'm basing the Stagonian army loosely on a French model, I've decided that Dragoons will be in red coats and Cavalry in blue coats.
Thus, for Dragoon standards, the bottom half will be red (for the coat color).
The upper half of the Dragoon standard will be in the regiment's facing color.
And the fringe (and hat tape color) will be in the button color.
Thus, the first Dragoon standard would be for a regiment with black facings to their red coats and brass buttons with yellow hat tape.
The second Dragoon unit would be similar to the first except that it would have yellow facings to their red coat.
Cavalry standards are square (rather than swallow-tailed). Like the Dragoon standards, the central device is the Stagonian Stag. But unlike the Dragoon standards, the stag is not on the Stagonian silver-blue of their national flag.
The white stag is on the unit's "facing color". And, again, the fringe is the same as the button (and hat tape) color.
Thus the first flag would be for a blue-coated regiment with gray facing color and silver buttons and white hat tape.
The second unit would have red facings with brass buttons and yellow hat tape.
Thus there once again is a "system" that connects the standards to the units they belong to.