There is also: Missing/accumulating data http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057406.html An NA compromise idea -- many-NA http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057408.html NEPaNEP lessons - was: alterNEP http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057435.html NA/Missing Data Conference Call Summary http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057474.html HPC missing data - was: NA/Missing Data Conference Call Summary http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057482.html using the same vocabulary for missing value ideas http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057485.html towards a more productive missing values/masked arrays discussion... http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057511.html miniNEP1: where= argument for ufuncs http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057513.html miniNEP 2: NA support via special dtypes http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057542.html Missing Data development plan http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057567.html Missing Values Discussion http://mail.scipy.org/pipermail/numpy-discussion/2011-July/057579.html NA masks for NumPy are ready to test http://mail.scipy.org/pipermail/numpy-discussion/2011-August/058103.html