chsize(si1)

chsize(si1, si2)
chsize(si1, si2, si3)

Change size of data, zero-fill or truncate.
DO NOT change the value of OFFSET and SPECW, so EXTRACT should
always be preferred on spectra (unless you know exactly what your are doing).

see also : extract modifysize

NPK Documentation, version 0.995 - 2009-10-14