Official colors

[Lothia]

Ave civitas,

I am wondering if there were specific colors for specific branches of the government.
I know that purple was reserved for the Imperials.
I think blue was reserved for some, if not all civil servants.
I am not sure if red was the official color of the army.  
Were maroon shoes restricted to sitting senators?
I am a little iffy about public display of factions colors, were they somehow identified by neck kerchiefs or the color of their shoe laces?
Were foreign ambassadors dressed differently from other officials?
Were there other colors or patterns that would be reserved for special offices, like were horse trainers wearing black and white checkered capes?

Is there some reference out there that could help me with this?

Again, thank you all in advance

[Robert Vermaat]

What period are you thinking about?

[Lothia]

OH, The end of the fourth, the beginning of the 5th century, AD.

[Robert Vermaat]

OH,  The end of the fourth, the beginning of the 5th century, AD.

Sorry but I have never heard of such colour distinctions apart from the purple of course.
White was worn at very official occasions (including the military).
Red seems to have been the dominant colour for undecorated tunics worn under armour, but others occur as well (such as blue for naval troops), including different colours for decorated tunics.
Never have I heard of civil servants wearing blue only? 
Same for maroon, or 'black and white checkered capes'.