Extraction of error spectrum in Sloan Digital Sky Survey I need to know does SDSS spectrum contains error spectrum as well?

http://www.sdss.org/dr12/spectro/spectro_basics/#AbouttheSpectra

The above link says, further HDU's contain error spectrum and than tells about the inverse variance. Does inverse variance contains error spectrum? If yes, how can I extract that, if not where can I find error spectrum?
The variance is the square of the standard deviation, so you can calculate 1$\sigma$ errors of the spectrum by taking the square root of one over the inverse variance of HDU1 (https://data.sdss.org/datamodel/files/SPECTRO_REDUX/RUN2D/PLATE4/spPlate.html#hdu1head). 

(You will get infinity for bad pixels since their inverse variance is set to zero.)