Employee Holiday on Personnel SubArea Level

Hi HR gurus,

Please help me with the following scenario. I have a personnel area by the name of let's say X and this personnel area has further 2 personnel sub-areas namely Y and Z respectively. Now last week on a particular day personnel sub area Z was off for all employees working in it , where as employees in Y personnel subarea were working as per normal schedule. How can I create a holiday specific to personnel sub-area ? Please help me on this.