2 DATA  
2.1 Observations and data reductions  
2.2 Photometry  
2.3 SDSS data  

3 ISOPHOT SOURCES IN NGP FIELDS  
3.1 Matching of FIR and optical/NIR sources  
3.2 Unambiguous bright galaxies  
3.3 Confused fields  

4 DISCUSSION  
4.1 The nature of unambiguous counterparts  
4.2 The nature of confused counterparts  
4.3 Higher redshift counterparts  
4.4 Comparing to previous surveys and models  
4.5 Models  
4.6 Confusion at FIR wavelengths