SDEF*INE—

This is the command to define a spectrum or histogram.
‘Spc?’ asks for each spectrum you wish to define individually. (This process will continue until you type return to get back to the main command level).

i.) One Dimensional Spectrum format

spc-name : par / div [off:len/type] c-nam
spc-name : par [len/type] c-nam
spc-name-- The name of the spectra, terminated by the symbol
par-- The parameter that the spectrum is making a histogram of.
div-- The division factor for the parameter. The value must be power of two. If absent, one is assumed.
off-- The offset value for the channels to take data for (0 is assumed if absent).
len-- The number of channels of the histogram.
type - Specifies the BPC of the spectrum
c-nam-- An optional condition that is to be satisfied before the spectrum can be incremented.

ii.) Two Dimensional Spectrum format

spc-name : x-par/x-div,y-par/y-div[x-off:x-len,y-off:y-len/type] c-nam
spc-name : x-par , y-par (x-off:x-len, y-off:y-len/type] c-nam
spc-name-- The name of the spectra, terminated by the symbol.
x-par-- The x parameter that the spectrum is making a histogram of.
x-div-- The division factor for the x parameter 1 absent)
x-off-- The offset in the x direction for the channels 0 if absent)
x-len-- The number of channels in the x direction of the spectrum.
y-par-- The y parameter that the spectrum is making a histogram of.
y-div-- The division factor for the y parameter
y-off-- The offset in the y direction for the channels
y-len-- The number of channels in the y direction of the spectrum.
type-- Specifies the BPC for the spectrum c-nam-- An optional condition that is to be satisfied before the spectrum can be incremented.

iii.) Bit Spectrum Format

spc-name : par B c-nam
spc-name-- The name of the spectra, terminated by the : symbol.
par-- The parameter that the spectrum is making a histogram of.
c-nam-- An optional condition that is to be satisfied before the spectrum can be incremented.

A bit spectrum is unusual in that the channels are not incremented according to the value of the parameter being used, but by the bits that are set within that parameter. A bit spectrum is always eighty-five channels long, although only every fifth channel actually gets used. The rest are for spacing purposes.  If bit zero of the parameter being examined is set, then channel 80 is incremented. If bit one is set, then channel 75 is set, etc. It’s usually used in examining which bits are getting set in the event bitmask.