Tell me about area qualification in sterile facility

Tell me about this and refer the guidelines

https://ec.europa.eu/health/medicinal_products/consultations/2020_sterile_medicinal_products_en

https://ec.europa.eu/health/sites/health/files/files/gmp/2020_annex1ps_sterile_medicinal_products_en.pdf

https://www.who.int/medicines/areas/quality_safety/quality_assurance/GMPSterilePharmaceuticalProductsTRS961Annex6.pdf

ISO14644-1,2 and 4. This guideline is referred to in Annex 1