[BioC] affy cel + cdf files content

[julien.sylvestre@wotan.ens.fr]

This message is not directly related to Bioconductor yet I hope it might be of general interest for users...

The first line of an Affymetrix Yg_s98 yeast chip .cel file looks like this
X	Y	MEAN	STDV	NPIXELS
0	0	232	45	36
I read about 100 pixels were used whereas it seems that no more than 36 are used here. 
How is the svd calculated ?

The first line of the corresponding .cdf file reads : 
X	Y	PROBE	PLEN	ATOM	INDEX	MATCH	BG
167	80	N	20	1	42887	0	0
Can anyone tell me the meaning of the last 6 columns.

Thanks in advance.

JS.