Expressions

arithmetic operators: + - * / **
relational operators: .EQ. .NE. .GE. .GT. .LE. .LT. == /= >= > <= <
logical (boolean) operators: .AND. .OR. .NOT. & $\vert$ #
brackets: use brackets, `(', `)', as appropriate,
sexagesimal values: use a colon (`:') to separate hours/degrees, minutes and seconds. Unsigned values are interpreted as hours; values in degrees must always have a sign (`+' or `-'). Sexagesimal values are converted to radians prior to evaluating the expression.
great circle distance: GREAT( $\alpha_{1},\delta_{1}$, $\alpha_{2},\delta_{2}$)
position angle of point $(\alpha_{2},\delta_{2})$ from point $(\alpha_{1},\delta_{1})$: PANGLE( $\alpha_{1},\delta_{1}$, $\alpha_{2},\delta_{2}$)