c	Subroutines to set all arguments sent to the isf_writ functions to null.
c	Real and float variables are set to the common block parameter ISF_NULL,
c	this parameter is set in 'isf_bul.h'.
c	Strings are set to a single space.
c	The write routines check for these values and use them to distinguish 
c	between zero and undefined arguments.

	subroutine nullify_data_type(data_type,subtype,data_format,subformat)

	character data_type*(*), subtype*(*), data_format*(*), subformat*(*)
	include 'isf_bul.h'

	data_type   = " "
	subtype     = " "
	data_format = " "
	subformat   = " "

	return
	end

	subroutine nullify_event_id(evid,region)

	character evid*(*),region*(*)

	evid   = " "
	region = " "

	return
	end

	subroutine nullify_origin(yyyy,mm,dd,hh,mi,ss,msec,timfix,stime,
&						sdobs,lat,lon,epifix,smaj,smin,strike,depth,depfix,
&						sdepth,ndef,nsta,gap,mindist,maxdist,antype,loctype,
&						etype,author,origid)

	character author*(*), origid*(*), etype*(*)
	character*1 timfix, epifix, depfix, antype, loctype
	integer yyyy, mm, dd, hh, mi, ss, msec
	integer strike, ndef, nsta, gap
	real stime, sdobs, lat, lon, smaj, smin, depth, sdepth
	real mindist, maxdist
	include 'isf_bul.h'

	yyyy   = ISF_NULL
	mm     = ISF_NULL
	dd     = ISF_NULL
	hh     = ISF_NULL
	mi     = ISF_NULL
	ss     = ISF_NULL
	msec   = ISF_NULL
	timfix = ' '
	stime  = ISF_NULL
	sdobs  = ISF_NULL
	lat    = ISF_NULL
	lon    = ISF_NULL
	epifix = ' '
	smaj   = ISF_NULL
	smin   = ISF_NULL
	strike = ISF_NULL
	depth  = ISF_NULL
	depfix = ' '
	sdepth = ISF_NULL
	ndef   = ISF_NULL
	nsta   = ISF_NULL
	gap    = ISF_NULL
	mindist = ISF_NULL
	maxdist = ISF_NULL
	antype = ' '
	loctype = ' '
	etype  = " "
	author = " "
	origid = " "

	return
	end

	subroutine nullify_origin_param(param,value,numparam)

	integer numparam
	character param(*)*(*),value(*)*(*)

	numparam = 0
	return
	end

	subroutine nullify_momten(scale_factor,scalar_moment,fclvd,
&								mrr,mtt,mpp,mrt,mtp,mpr,nsta1,nsta2,author,
&								scalar_moment_unc,fclvd_unc,mrr_unc,mtt_unc,
&								mpp_unc,mrt_unc,mtp_unc,mpr_unc,ncomp1,
&								ncomp2,duration)
	character author*(*)
	integer scale_factor,nsta1,nsta2,ncomp1,ncomp2
	real scalar_moment,fclvd,mrr,mtt,mpp,mrt,mtp,mpr
	real scalar_moment_unc,fclvd_unc,mrr_unc,mtt_unc,mpp_unc
	real mrt_unc,mtp_unc,mpr_unc,duration
	include 'isf_bul.h'

	scale_factor  = ISF_NULL
	scalar_moment = ISF_NULL
	fclvd         = ISF_NULL
	mrr           = ISF_NULL
	mtt           = ISF_NULL
	mpp           = ISF_NULL
	mrt           = ISF_NULL
	mtp           = ISF_NULL
	mpr           = ISF_NULL
	nsta1         = ISF_NULL
	nsta2         = ISF_NULL
	author = " "

	scalar_moment_unc = ISF_NULL
	fclvd_unc         = ISF_NULL
	mrr_unc           = ISF_NULL
	mtt_unc           = ISF_NULL
	mpp_unc           = ISF_NULL
	mrt_unc           = ISF_NULL
	mtp_unc           = ISF_NULL
	mpr_unc           = ISF_NULL
	ncomp1            = ISF_NULL
	ncomp2            = ISF_NULL
	duration          = ISF_NULL

	return
	end

	subroutine nullify_fault_plane (f_type,strike,dip,rake,np,ns,
&															f_plane,author)

	character f_plane*(*), f_type*(*), author*(*)
	integer np,ns
	real strike,dip,rake
	include 'isf_bul.h'

	f_type = " "
	strike = ISF_NULL
	dip    = ISF_NULL
	rake   = ISF_NULL
	np     = ISF_NULL
	ns     = ISF_NULL
	f_plane = " "
	author  = " "

	return
	end

	subroutine nullify_axes(scale_factor,t_val,t_azim,t_pl,b_val,
&									b_azim,b_pl,p_val,p_azim,p_pl,author)

	character author*(*)
	integer scale_factor
	real t_val,t_azim,t_pl,b_val,b_azim,b_pl,p_val,p_azim,p_pl

	include 'isf_bul.h'

	scale_factor = ISF_NULL
	t_val    = ISF_NULL
	t_azim   = ISF_NULL
	t_pl     = ISF_NULL
	b_val    = ISF_NULL
	b_azim   = ISF_NULL
	b_pl     = ISF_NULL
	p_val    = ISF_NULL
	p_azim   = ISF_NULL
	p_pl     = ISF_NULL
	author = " "

	return
	end

	subroutine nullify_axes_err(t_val_unc,t_azim_unc,t_pl_unc,b_val_unc,
&					b_azim_unc,b_pl_unc,p_val_unc,p_azim_unc,p_pl_unc,fclvd)

	real t_val_unc,t_azim_unc,t_pl_unc,b_val_unc,b_azim_unc,b_pl_unc
	real p_val_unc,p_azim_unc,p_pl_unc,fclvd

	include 'isf_bul.h'

	t_val_unc  = ISF_NULL
	t_azim_unc = ISF_NULL
	t_pl_unc   = ISF_NULL
	b_val_unc  = ISF_NULL
	b_azim_unc = ISF_NULL
	b_pl_unc   = ISF_NULL
	p_val_unc  = ISF_NULL
	p_azim_unc = ISF_NULL
	p_pl_unc   = ISF_NULL
	fclvd      = ISF_NULL

	return
	end

	subroutine nullify_effects(heard,felt,damage,casualties,uplift,
&				subsidence,fault,tsunami,seiche,volcano,acoustic,gravity,
&				t_wave,liquification,geyser,landslide,sandblow,cracks,lights,
&				odours,loctype,lat,lon,dist,azim,country,postcode,net,
&				sta,intensity1,modifier,intensity2,scale,author)

	character author*(*),loctype*(*)
	character scale*(*),country*(*),postcode*(*),net*(*),sta*(*)
	character heard,felt,damage,casualties,uplift,subsidence,fault,tsunami
	character seiche,volcano,acoustic,gravity,t_wave,liquification,geyser
	character landslide,sandblow,cracks,lights,odours
	character modifier
	real lat,lon,dist,azim,intensity1,intensity2

	include 'isf_bul.h'

	heard      = ' '
	felt       = ' '
	damage     = ' '
	casualties = ' '
	uplift     = ' '
	subsidence = ' '
	fault      = ' '
	tsunami    = ' '
	seiche     = ' '
	volcano    = ' '
	acoustic   = ' '
	gravity    = ' '
	t_wave     = ' '
	liquification = ' '
	geyser     = ' '
	landslide  = ' '
	sandblow   = ' '
	cracks     = ' '
	lights     = ' '
	odours     = ' '
	loctype    = " "
	lat   = ISF_NULL
	lon   = ISF_NULL
	dist  = ISF_NULL
	azim  = ISF_NULL
	country  = " "
	postcode = " "
	net = " "
	sta = " "
	intensity1 = ISF_NULL
	modifier = ' '
	intensity2 = ISF_NULL
	scale  = " "
	author = " "

	return
	end

	subroutine nullify_netmag(magtype,magind,mag,magerr,nsta,author,origid)

	character magtype*(*), author*(*), origid*(*)
	character magind
	real mag,magerr
	integer nsta

	include 'isf_bul.h'

	magtype = " "
	magind = ' '
	mag    = ISF_NULL
	magerr = ISF_NULL
	nsta   = ISF_NULL
	author = " "
	origid = " "

	return
	end

	subroutine nullify_netmag_sta(sta,n)

	integer n
	character sta(*)*(*)

	n = 0
	return
	end

	subroutine nullify_netmag_basis(param,value)

	character param*(*), value*(*)

	param = " "
	value = " "

	return
	end

	subroutine nullify_phase(sta,dist,esaz,phase,hh,mi,ss,msec,timeres, 
&				azim,azimres,slow,slowres,timedef,azimdef,slowdef,snr,amp,
&				per,picktype,sp_fm,detchar,magtype,magind,mag,arrid)

	character sta*(*),arrid*(*),phase*(*),magtype*(*)
	character timedef,azimdef,slowdef,sp_fm,detchar,magind,picktype
	real dist,esaz,timeres,azim,azimres,slow,slowres,snr,amp,per,mag
	integer hh,mi,ss,msec

	include 'isf_bul.h'

	sta     = " "
	dist    = ISF_NULL
	esaz    = ISF_NULL
	phase   = " "
	hh      = ISF_NULL
	mi      = ISF_NULL
	ss      = ISF_NULL
	msec    = ISF_NULL
	timeres = ISF_NULL
	azim    = ISF_NULL
	azimres = ISF_NULL
	slow    = ISF_NULL
	slowres = ISF_NULL
	timedef = ' '
	azimdef = ' '
	slowdef = ' '
	snr     = ISF_NULL
	amp     = ISF_NULL
	per     = ISF_NULL
	picktype = ' '
	sp_fm    = ' '
	detchar  = ' '
	magtype  = " "
	magind   = ' '
	mag      = ISF_NULL
	arrid    = " "

	return
	end

	subroutine nullify_phase_measure(param,value,numparam)

	integer numparam
	character param(*)*(*),value(*)*(*)

	numparam = 0

	return
	end

	subroutine nullify_phase_origid(origid)

	character origid*(*)

	origid = " "

	return
	end

	subroutine nullify_phase_info(net,chan,filter,filter_min,
&					filter_max,phase,yyyy,mm,dd,time_unc,time_weight, 
&					azim_unc,azim_weight,slow_unc,slow_weight,amp_unc,
&					per_unc,mag_unc,author,arrid)

	character net*(*),chan*(*),author*(*),arrid*(*),phase*(*)
	character filter
	real filter_min,filter_max,time_unc,time_weight,azim_unc,azim_weight
	real slow_unc,slow_weight,amp_unc,per_unc,mag_unc
	integer yyyy,mm,dd

	include 'isf_bul.h'

	net    = " "
	chan   = " "
	filter = ' '
	filter_min  = ISF_NULL
	filter_max  = ISF_NULL
	phase  = " "
	yyyy        = ISF_NULL
	mm          = ISF_NULL
	dd          = ISF_NULL
	time_unc    = ISF_NULL
	time_weight = ISF_NULL
	azim_unc    = ISF_NULL
	azim_weight = ISF_NULL
	slow_unc    = ISF_NULL
	slow_weight = ISF_NULL
	amp_unc     = ISF_NULL
	per_unc     = ISF_NULL
	mag_unc     = ISF_NULL
	author = " "
	arrid  = " "

	return
	end

	subroutine nullify_phase_min(timeoffset,azoffset,
&							slowoffset,ampoffset,peroffset,magoffset)

	real timeoffset,azoffset,slowoffset,ampoffset,peroffset,magoffset

	include 'isf_bul.h'

	timeoffset = ISF_NULL
	azoffset   = ISF_NULL
	slowoffset = ISF_NULL
	ampoffset  = ISF_NULL
	peroffset  = ISF_NULL
	magoffset  = ISF_NULL

	return
	end

	subroutine nullify_phase_max(timeoffset,azoffset,
&							slowoffset,ampoffset,peroffset,magoffset)

	real timeoffset,azoffset,slowoffset,ampoffset,peroffset,magoffset

	include 'isf_bul.h'

	timeoffset = ISF_NULL
	azoffset   = ISF_NULL
	slowoffset = ISF_NULL
	ampoffset  = ISF_NULL
	peroffset  = ISF_NULL
	magoffset  = ISF_NULL

	return
	end

	subroutine nullify_phase_correc(timecorr,azcorr,
&							slowcorr,ampcorr,percorr,magcorr)

	real timecorr,azcorr,slowcorr,ampcorr,percorr,magcorr

	include 'isf_bul.h'

	timecorr = ISF_NULL
	azcorr   = ISF_NULL
	slowcorr = ISF_NULL
	ampcorr  = ISF_NULL
	percorr  = ISF_NULL
	magcorr  = ISF_NULL

	return
	end

	subroutine nullify_phase_original(chan,sta,yyyy,mm,
&								dd,hh,mi,ss,msec,azim,slow,amp,per,mag)

	character sta*(*),chan*(*)
	real azim,slow,amp,per,mag
	integer yyyy,mm,dd,hh,mi,ss,msec

	include 'isf_bul.h'

	chan  = " "
	yyyy  = ISF_NULL
	mm    = ISF_NULL
	dd    = ISF_NULL
	hh    = ISF_NULL
	mi    = ISF_NULL
	ss    = ISF_NULL
	msec  = ISF_NULL
	azim  = ISF_NULL
	slow  = ISF_NULL
	amp   = ISF_NULL
	per   = ISF_NULL
	mag   = ISF_NULL

	return
	end

	subroutine nullify_comment(comment)

	character comment*(*)

	comment = " "

	return
	end