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		phastCons data files contain the compressed 
		conservation scores that underlie the Conservation annotation
		track and the phastCons table. For a detailed description
		of the algorithm used to produce the scores, see the
		Genome Browser description page associated with the 
		Conservation track. 
		 
		File Format (assemblies released Nov. 2004 and later)
		 
		When uncompressed, the file contains a declaration line and
		one column of data in wiggle table fixed-step format: 
		  fixedStep chrom=scaffold_1 start=3462 step=1
  0.0978 
  0.1588
  0.1919
  0.1948 
  0.1684  
		1. Declaration line:  The declaration line specifies the 
		starting point of the data in 
		the assembly. It consists of the following fields:
		 
		A new declaration line is inserted in the file when the 
		chrom value changes, when a gap is encountered 
		(requiring a new start value), or when the 
		step interval changes.
		fixedStep -- keyword indicating the wiggle
		track format used to write the data. In fixed step
		format, the data is single-column with a fixed
		interval between  values.
		
		chrom --  chromosome or scaffold on which 
		first value is located.
		
		start -- position of first value on 
		chromosome or scaffold specified by chrom. NOTE: 
		Unlike most Genome Browser coordinates, these are one-based.
		
		step -- size of the interval (in bases) 
		between values.
		 
		2. Data lines: The first data value below the header 
		shows the score 
		corresponding to the position specified in the header. 
		Subsequent score values step along the assembly in one-base 
		intervals. The score shows the posterior probability that 
		phastCons's phylogenetic hidden Markov model (HMM) is in its 
		most-conserved state at that base position.
		 
		 File Format (assemblies prior to Nov. 2004)
 
		When uncompressed, the data file contains two columns:
		
		  294	0.0953	
  295	0.0948	
  296	0.0943	
  297	0.0936	
  298	0.0929	
  299	0.0921Column #1 contains a one-based position coordinate.
		Column #2 contains a score showing the posterior probability 
		that phastCons's phylogenetic hidden Markov model (HMM) is in 
		its most conserved state at that base position. 
		 References for phastCons
 
		Siepel A and Haussler D (2005). Phylogenetic hidden Markov 
		models. In R. Nielsen, ed., Statistical Methods in Molecular
		Evolution, pp. 325-351, Springer, New York.  
		Siepel, A., Bejerano, G., Pedersen, J.S., Hinrichs, A., Hou, M.,
		Rosenbloom, K., Clawson, H., Spieth, J., Hillier, L.W., 
		Richards, S., Weinstock, G.M., Wilson, R. K., Gibbs, R.A., Kent,
		W.J., Miller, W., and Haussler, D.
		Evolutionarily conserved elements in vertebrate, 
		insect, worm, and yeast genomes.
		Genome Res. 15, 1034-1050 (2005). 
		For a discussion of the methods used to calculate the 
		phastCons scores, see the description page for the hg17 
		Conservation track in the Genome Browser.
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