[xsl] How to escape the normal interpretation of parentheses when utilizing regex-group()?

["Roger L Costello costello@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Hi Folks,

My input consist of lines of text. Here is a sample input:

1 Record Type

The XSLT program is to transform that line into this XML:

<column>1</column>
<field-name>Record Type</field-name>

Here is another sample input:

2 thru 4 Customer/Area Code

The XSLT program is to transform that line into this XML:

<column>2 thru 4</column>
<field-name>Customer/Area Code</field-name>

I figured that <xsl:analyze-string and regex-group() would be suitable for
breaking apart each line.

What regex to use for column? The value of column is an integer followed
optionally by "thru" and another integer. I figured this regex should do the
job:

([0-9]+(\s+thru\s+[0-9]+)?)

But, but, but, ....

regex-group(1) means that whole regex. So with this input:

2 thru 4 Customer/Area Code

regex-group(1) matches:

2 thru 4

Perfect.

Unfortunately, regex-group(2) matches the inner, optional part. So I end up
with this:

<column>2 thru 4</column>
<field-name> thru 4</field-name>

Eek!

Wrong.

How to solve this problem? Is there a way to specify that the inner, optional
part:

(\s+thru\s+[0-9]+)?

belongs only to regex-group(1), not to regex-group(2)?

Stated another way, is there a way to indicate that the parentheses in the
inner, optional part are not to be considered as regex-group() syntax?

Stated still another way, is there a way to "escape" the normal interpretation
of parentheses when utilizing regex-group()?

/Roger