const as string?

[programandala.net]

I got the following error with both 1.2.5 and 1.2.6:

"Initializer expression is not constant"

The line is:

const prompt as string = chr(18,1,62,18,0,8)

I supossed the reason is the chr() calculation, so I put a literal string instead:

const prompt as string = "my prompt"

but nothing changed, the error remains.

The wiki page on CONST is not written, so I searched for CONST in the sources for examples. I searched all the sources for a "const as string" example (using a regular expression), but found nothing.

Are constant strings forbidden?