schedwhen is giving me a segmentation fault, at least in Csound6. 

P 

;from the manual

<CsoundSynthesizer>

<CsOptions>

; Select audio/midi flags here according to platform

-odac     ;;;realtime audio out

;-iadc    ;;;uncomment -iadc if realtime audio input is needed too

; For Non-realtime ouput leave only the line below:

; -o schedwhen.wav -W ;;; for file output any platform

</CsOptions>

<CsInstruments>

sr = 44100

ksmps = 32

nchnls = 2

0dbfs  = 1

instr 1

kmtr metro 100 ;produce 100 triggers per second

     schedwhen kmtr, 2, 1, .3 ;but schedwhen plays instr. 2 only once

endin

instr 2                                            

aenv linseg 0, p3*.1, 1, p3*.3, 1, p3*.6, 0 ;envelope

a1   poscil .3*aenv, 1000, 1

     outs a1, a1

endin

</CsInstruments>

<CsScore>

f 1 0 16384 10 1 ;sine 

i 1 0 3

i 1 3 5

e

</CsScore>

</CsoundSynthesizer>