did a substained spell ceased to function when you pass an astral barrier?

in MiTS p83 there are examples to what happen for dual natured characters or foci passing an astral barrier but not for basic substained spell. it seems to me that astral barrier blocks only astral forms (that s dual being, projected magicians, foci and astral barrier) and as spell aren t astral forms but just auras appearing on their target (they arent solid on the astral plane) i dont see any reason for barriers to block them (except those maintened by a substaining focus which is an astral form)

but on page 83 we can read "if a mundane character with a spell substained on it pass a barrier the spell is stopped" so i dont understand anything at all that doesnt seem in accordance with the astral logic of SR3!!!

in addition why anchored spells which arent astral forms are stopped by barriers??
can somene explain me?

please answer only if you re sure of yourself (ie you re a shadowrun gourou wink.gif )