[xsl] Save regex in variable

["KrustyDerClown" <KrustyDerClown@xxxxxx>]

Hello,

i want to save a regex in a variable. Is that possible ?

I have the following code:

<xsl:analyze-string select="commit/comment" regex="(OK|ER)[0-9]+" flags="i">

And i want to save the regex into a variable at the beginning of the 
document. Is that possible ?

I try:

<xsl:variable name="regex" select="'(OK|ER)[0-9]+'" />

But this is a string and works only, when i give a regex as string value 
like here:

<xsl:if test="matches(commit/comment,$regex,'i')">

Can anyone help me ?

Thank you for your support.

Greets Oliver