filter and filter-out functions do they preserve order

[Krzysztof Cieniuch]

Hi,

Short question as in subject does filter function preserves original 
elements order
I did some tests like:
org:= a b c d e
res:=$(filter a d c,$(org))
$(info $(res))

and this prints  a c d so it looks like it preserves order but can I 
relay on that
or is this just coincidence in my simple example ?

Thanks
Chris