Need to execute the code inside XSLT exactly once.

[Jayesh Bhapkar]

Hi,
How to execute the code in XSLT exactly once inside xsl:for-each ?

During transformation, I need to check for existence of some value (inside xsl:for-each), if value exists do some operation, if it doesn't I need to do some other operation but only once.
Is there any way to do the same in XSLT ?

(Using <xsl:otherwise> is not an option here since, it will repeat the operation as many times the xsl:for-each runs)

Any sort of help is highly appreciated.

Thanks,
Jayesh