World: r3wp

That is not possible, but you can determine presedence of use in 
the function body, so the outcome would be the same, or you could 
make an error, if both refinements are used.

>> a: func [/b /c] [if all [b c] [make error! "Only one refinement 
can be used."]]
>> a
== none
>> a/b
== none
>> a/c
== none
>> a/b/c
** User Error: Only one refinement can be used.
** Near: make error! "Only one refinement can be used."

Endo, launch with parameters stopped workng years ago.  So, we had 
to move to call instead

GrahamC: Thanks. I'll keep that in mind.

@Henrik : thanks a lot !

nve, there is a built-in error that might be better for you to use. 
Try this:
>> cause-error 'script 'bad-refines none
** script error: incompatible or invalid refinements

That error is apparently not in R2 though, sorry.

nve, there's TOO-MANY-REFINES in R2:

>> cause-error 'script 'too-many-refines none
** Script Error: Too many refinements

Is there a way to avoid conversion of numbers to scientific notation 
by mold?
>> mold 0.004
== "4E-3"


or have you a function to convert back a string representing a number 
with exponent to one eithout it?

eithout = without

You have to do it yourself.

Many people have examples and funcs out there for it.

http://www.rebol.org/view-script.r?script=format-decimal.r

I have a general FORMAT func I use, but it's quite heavy as it handles 
a lot of things.

Thanks. The one from Nick should be ok.

You can also check

http://www.rebol.org/view-script.r?script=printf.r

I've also put a format-number function that I use on Checklists on 
Altme. It works well for me.
>> format-number 1 / 3
== "0.333333333333333"

Under Checklists / Code Snippets.

The function by Nick is a little slow since I have a lot of numbers. 
This is faster but not very fast:

format-decimal: func [x /local e q] [
	x: form x
    if find x "E-" [ 
		e: to-integer next next q: find x "E-"
		clear q
		remove find x "."
		if #"-" = first x [x: next x]
		insert/dup x "0" e
		insert next x "."
	]
	head x
]

The idea from Ladislav is nice but I would like most a more "rebol" 
solution.

Scientific notation of numbers and automatic reformating time! values 
(00:00:00 --> 0:00) are the most annoying parts of REBOL for me.
It would be more useful if it doesn't happen when FORMing.

Is there a possibility for cyrillic/Russian at Rebol/View except 
for pixelart drawing the characters?

In R3/View, but it's currently buggy and limited to Windows and Amiga

Since you'd have to switch languages anyway, you could also consider 
Red with the GTK+ binding

Uh. In Red, everything is possible with any bindings