Seaboard System theme from Railroad Signals of the US website based on SpDrS60 theme. The following signal masts are supported:-

Prefix	Mast type
	Single head mast automatic
1a_	Single head mast standard head aspect numbers
1_	Single head mast unified Seaboard aspect numbers
2_	Twin head mast unified Seaboard aspect numbers
3_	Triple head mast unified Seaboard aspect numbers

Automatic aspect numbers
-r	R292	red
-y	R285	yellow
-g	R281	green
-w	R290	lunar
-b	-	unlit


Standard head aspect numbers
-0	R291/2/4/5	red
-1	R285		yellow
-2	R405		green
-3	R290		lunar
-8	-		unlit

Unified Seaboard aspect numbers
-0	R291/2/4/5	red / (red) / (red)
-1	R290		(red) / (red) / lunar
-2	R288		red / red / yellow
-3	R287		red / red / green
-4	R286		red / yellow / (red)
-5	R285		yellow / (red) / (red)
-6	R284		yellow / red / green
-7	R283b		red / yellow / green
-8	R283a		red / yellow / yellow
-9	R283		red / green / (red)
-10	R282a		yellow / yellow / (red)
-11	R282		yellow / green / (red)
-12	R286		red / yellow / (red)
-13	R281c		red / flashing green / (red)
-14	R281b		yellow / flashing green / (red)
-15	R281		green / (red) / (red)
-16	-		unlit
