File Extension in SQL*PLus Script

I am running a SQL*Plus script, which outputs an HTML-Formatted file. I can get it to create a .html extension in UNIX, but not NT. Can someone tell me what I need to do to effect this?

This is 8.1.7.

COLUMN A1 NOPRINT NEW_VALUE DATO;
SELECT TO_CHAR(SYSDATE - 1,'MMDDYY') A1 FROM DUAL; SPOOL x:&DATO\.html -- Escape works in Unix, but not NT Received on Mon Oct 28 2002 - 07:56:05 CST