###TREE RING UTILITIES
###################################

#1. make.crn - makes time series from *.crn format allowing for some oddball formats.
	#this is a very old script and could be updated
#2. make.rwl_new - makes organized measurement data set from Tucson format (allowing for some oddball formats)
        #update of make.rwl
#3. countrycode - utility used in make.crn, make.rwl to look up country code from identification form
#4. RCS.chronology - emulation of RCS chronology with several methods. I usually use method="nls"
#5. jacoby.chronology - emulaiton of "conventional" chronology using modified neg exp. This has been tested carefully.
#6. countf #utility to give time series of ring counts
#7. agef - utility to calculate ring age from rwl file
#   some older functions seldom used


#############
#1. make.crn

make.crn<-function(loc,widths0=c(6,4,rep( c(4,3),10)),N= -1,readtype="REG",url0="ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/chronologies") {
             #may need some more quality control on oddballs but will work for STNDRD, SCHW, Long
	
	if(url0=="ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/updates")  url<-file.path(url0,paste(loc,"crn",sep="."))	else url<-file.path(url0,countrycode(loc),paste(loc,"crn",sep="."))

        #see if it is a Schweingruber format by checking fifth row
	schwein<-c("RAW","RES","STD")
	h<-try(readLines(url,n=5))
	if (class(h)=="try-error") make.crn<-NA else {
	  if( substr(h[4],6,6)=="-") readtype<-"LONG"
	  type<-substr(h,83,85)
	  if ( !is.na( match(type[5],schwein) ) )  readtype<-"SCHW"} 
 
    	#read in different ways for STNDRD and SCHW formats
		#SCHW format has a number of options; only the RAW version is read here
		#this is controlled by calculating N in Schwein case; otherwise N= -1 in STNDRD
   	if(readtype=="SCHW") { h<-readLines(url);
		temp<-(substr(h,83,85)=="STD")
		h=h[temp]
		h=h[4:length(h)]		
		write.table(h,"temp.dat",row.names=FALSE,quote=FALSE,col.names=FALSE)
		test=read.fwf("temp.dat",widths=c(6,4,rep(c(4,3),10)))
		start0=floor(test[1,2]/10)*10
		test=test[,seq(3,21,2)];dim(test)
		test=ts(c(t(test)),start=start0)
		temp=(test>=9990);test[temp]=NA
		temp=!is.na(test);r0=range( time(test)[temp])
		temp=(time(test)>=r0[1])&(time(test)<=r0[2])
		make.crn=ts(test[temp],start=r0[1])
		}
	if(readtype=="LONG") widths0[1:2]<-c(5,5)
	if(!(readtype=="SCHW")) {
	  h<-read.fwf(url,widths=widths0,skip=3,nrow=N,blank.lines.skip=TRUE,colClasses=c("factor",rep("numeric",21)))
			#blan.lines.skip added June 2006
	  start1<-h[1,2] #}
	  temp<-!is.na(h[,1])
	  h<-h[temp,]  #adjusts for blank lines
	  if (h[nrow(h),2]< h[(nrow(h)-1),2]) h<-h[1:(nrow(h)-1),]
		#this adjusts for some versions which have statistics in last row	

	  chron.crn<-h[,seq(3,21,2)]
	  if (start1>2000) print(loc, "ERROR 1 - START AFTER 2000")
	  temp<-(chron.crn==9990)
	  chron.crn[temp]<-NA
	  chron.crn<- c(t(chron.crn))
	  temp<-!is.na(chron.crn);
	  make.crn<- ts(chron.crn[temp],start=start1)
	  }
  	make.crn
	}

    #EXAMPLE
	#chron.crn<-make.crn("arge048")

##################
#2. make.rwl_new 

make.rwl_new =function(url,skip0=0,widths0 =c(8,4,rep(6,10))) { # "id","year","rw"
	trailer.verify<- 999
	trailing.marker<- (-9999)
	h<-try(readLines(url,n=5))
	if (class(h)=="try-error") make.rwl<-NA else {
	  tree<-read.fwf(file=url,widths=widths0,fill=TRUE,skip=skip0,blank.lines.skip=TRUE) 
	  levels(tree[,1])<-sub(" +$", "",levels(tree[,1]));

  	temp<-is.na(tree[,1])  #typically 0 and next segment is not invoked
	if(sum(temp)>0) tree<-tree[!temp,]

	(test3=sapply(tree,class)[2:12]); 
	if (sum(!is.na(match(test3,"factor")))>0) {
	  fred=readLines(url); fred=fred[!(fred=="")];
	  fred=fred[4:length(fred)];  n=nchar(fred);treeid=substr(fred,1,8);treeid=gsub(" +$","",treeid)
	  fred=substr(fred,9,n)
	  fred=gsub("-9999"," -99 ",fred)
	  write.table(fred,"temp.dat",quote=FALSE,row.names=FALSE,col.names=FALSE)
	  tree=read.table("temp.dat",fill=TRUE)
	  tree[tree== -99]= -9999
          tree=data.frame(treeid,tree)
         }

      #check for trailing 999 markers; very annoying; also -9999 trailers
	id=levels(tree[,1]);K=length(id);K #1022
 	names(tree)[1:2]=c("id","year")
	long=NULL

	for(i in 1:K) {
  	  temp=(tree[,1]== levels(tree[,1])[i])
	  test=tree[temp,]
	  A=outer(test[,2], 0:9, function(x,y) x+y) 
	  working=cbind( c(t(A)), c(t(test[,3:12])) )
	  M=nrow(working);M
	  temp1=!is.na(match(1:M,1:10)) & is.na(working[,2]);sum(temp1)
	  temp2=!is.na(match(1:M,(M-9):M )) & (is.na(working[,2])|(working[,2]== -9999)) ;sum(temp2)
	  working=working[!temp1&!temp2,]
	  working=data.frame( working); working$id=levels(tree[,1])[i]
	  long=rbind(long,working) 
	 }
	 
	 long=long[,c(3,1,2)];names(long)=c("id","year","rw")
	  make.rwl_new=long
	  make.rwl_new
 	}
	}
	#tree<-make.rwl("russ022w")
	#save(tree,file="d:/climate/data/briffa.2008/TornFin.rwl.tab")

############################
#3. countrycode: utility used in making crn and rwl 

download.file("http://www.climateaudit.org/scripts/tree/country.code.tab","temp.dat",mode="wb");load("temp.dat")
countrycode<-function(id) {
	temp<-match(substr(id,1,4),country.list[,1])
	if(is.na(temp)) countrycode<-"northamerica/usa" else countrycode<- country.list[temp,2]
	countrycode
	}


#############################
#4. RCS.chronology

RCS.chronology<-function (tree,method,parameters=NULL,interval=5,units=1) {
	dimnames(tree)[[2]][4]<-"x"
	tree<-tree[!is.na(tree$x),]
	tree$agegroup<-median(1:interval)+interval*trunc( (tree$age-1)/interval)
	tree$id<-factor(tree$id)
	tree$agegroupf<-factor(tree$agegroup)
	#year5f<-factor(tree$group)
	year5avg <-tapply(tree$x,tree$agegroupf,mean,na.rm=TRUE)/units
	agegroup<-as.numeric(names(year5avg))
	N<-length(agegroup)

	z<-cbind(agegroup,year5avg)	
	z<-data.frame(z)
	if (method=="mod.neg.exp") {fm <- nls( year5avg ~ A+B*exp(-C*agegroup),data = z,
		start = list(A=mean(z$year5avg)/4, B = mean(z$year5avg), C= .01 ),
		alg = "default", trace = TRUE,control=nls.control(maxiter=200, tol=1e-05, minFactor=1e-10)); 
		B<-coef(fm); 
		fitted<- B[1]+B[2]*exp(-B[3]*(1:agegroup[N]))  }
	if (method=="nls") {fm <- nls(x ~ A+B*exp(-C*age),data = tree,
		start = list(  A=mean(tree$x,na.rm=T)/4,B = mean(tree$x,na.rm=T), C= .01 ),
		alg = "default", trace = TRUE,control=nls.control(maxiter=200, tol=1e-05, minFactor=1e-10)); 
		B<-coef(fm); 
		fitted<- B[1]+B[2]*exp(-B[3]*(1:max(tree$age)))  }
	if (method=="linear") {fm<-lm(year5avg~agegroup,data=z);
		B<-coef(fm); fitted<-B[1]+B[2]*(1:agegroup[N])}
	if (method=="briffa") { B<-parameters;
 		if (length(B) ==2) fitted<- B[1]+B[2]*(1:agegroup[N]);
		if (length(B) ==3) fitted<- B[1]+B[2]*exp(-B[3]*(1:agegroup[N])) }
	if (method=="RCS.spline") { if(!is.null(parameters))  p<-spline.response(parameters[1]*N)  else  p<-spline.response(.66667*N)
		fit.model<- smooth.spline( agegroup, year5avg, spar = (1-p));
		fitted<-predict(fit.model,(1:agegroup[N]))$y;
		B<-fitted}
	fitted<-ts( fitted, start=1, end=agegroup[N])
	tree$delta<-NA
	tree$smooth<-NA
	for (k in 1:length(levels(tree$id))) {
		temp<-(tree$id==levels(tree$id)[k])
		y<-tree$year[temp]
		w<-tree$x[temp]
		n<-length(w);
		tree$smooth[temp]<-fitted[tree$age[temp]] 
		tree$delta[temp]<-w / tree$smooth[temp]
		}
	yearf<-factor(tree$year)
	series<-tapply(tree$delta,yearf,mean,na.rm=TRUE)
	series<-ts(series,start=min(tree$year),end=max(tree$year))	
	RCS.chronology<-list(series,z,tree$delta,tree$smooth,B,method)
	names(RCS.chronology)<-c("series","hist.curve","delta","smooth","coefficients","method")
	RCS.chronology
	}

################################
#5. jacoby.chronology 	#this fits with straight lines and negative exponentials

jacoby.chronology<-function(tree,method.chron="neg.exp")  {
	tree$delta<-NA
	tree$smooth<-NA
	dimnames(tree)[[2]][4]<-"x"
	temp.na<-is.na(tree$x)
	treef<-factor(tree$id)
	N<-length(levels(treef))
	jac.coef<-array(NA,dim=c(N,3))
	for (k in 1:N) {
		temp<-(tree$id[!temp.na]==levels(treef)[k])
		age<-tree$age[!temp.na][temp]
		w<-tree$x[!temp.na][temp]
		n<-length(w);
		Data<-cbind(age,w)
		Data<-data.frame(Data)
		fm1<-lm(w~age,data=Data)
		if (method.chron=="linear") {fit<-coef(fm1)[1]+coef(fm1)[2]*age;jac.coef[k,1:2]<-coef(fm1)}
		
		if(method.chron=="neg.exp") {
		   if (fm1$coefficients[2]>0) {fit<-rep(mean(w),length(age));jac.coef[k,1:2]<-c(mean(w),0)} else {
			fm <- try( nls( w ~ A+B*exp(-C*age),data = Data,
			start = list( A = fm1$coefficients[1]+fm1$coefficients[2]*200, B= - fm1$coefficients[2]*200, C=0.01 ),
			alg = "default", trace = TRUE,control=nls.control(maxiter=200, tol=1e-05, minFactor=1e-10)));

			if (class(fm)=="try-error") {fit<-rep(mean(w),length(age));jac.coef[k,1:2]<-c(mean(w),0)} else
				{a<-summary(fm)$parameters[,1];
				fit<-a[1]+a[2]*exp(-a[3]*age);
				jac.coef[k,]<-a	}
			} #else
				} #neg.exp
		tree$smooth[!temp.na][temp]<-fit
		tree$delta [!temp.na][temp]<-w/tree$smooth[!temp.na][temp]
		}
	yearf<-factor(tree$year)
	series<-tapply(tree$delta,yearf,mean,na.rm=TRUE)
	series<-ts(series,start=min(tree$year),end=max(tree$year))	
	row.names(jac.coef)=levels(treef)
	jacoby.chronology<-list(series,tree$delta,tree$smooth,jac.coef)
	names(jacoby.chronology)<-c("series","delta","smooth","coef")
	jacoby.chronology
	}

####################
#6. countf - return time series of tree counts

countf=function(tree,year=NULL) {
	   if(class(year)=="NULL") year=min(tree$year):max(tree$year)
	   count= ts( tapply(!is.na(tree$rw),factor(tree$year,levels=year),sum)	,start=min(year))
	   count[is.na(count)]=0
	   return(count)
	}

########################
#7. agef - function to return age of each ring as column in database

	agef=function(tree) {
	  tree$age=factor(tree$id)
	  levels(tree$age)=tapply(tree$year,tree$id,min)
	  tree$age=as.numeric(as.character(tree$age))
	  tree$age=tree$year-tree$age+1
	  tree=tree[,c(1,2,4,3)]
   	  return(tree)
	}


#################################################
#################################################
## OLDER FUNCTIONS THAT I SELDOM USE ANYMORE
	
#collate
	#FUNCTION TO COLLATE LONG TO TIME SERIES FORM
  		#this takes long-form and collates to time series
  #FUNCTION TO COLLATE LONG TO TIME SERIES FORM
  #this takes long-form and collates to time series

#FUNCTION TO COLLATE LONG TO TIME SERIES FORM
  #this takes long-form and collates to time series
  collate<-function(tree,START=1) {
	treef<-factor(tree[,1])
	M<-length(levels(treef))
	recon<-NULL
	name<-NULL

	for (j in 1:M) {
	  temp<-(tree$id==levels(treef)[j])&(tree$year>START)
	  if (sum(temp)>0) {
	     treetest<-tree[temp,];
	     treetemp<-ts (  rep(NA,max(treetest[,2])- min(treetest[,2])+1), start=min(treetest[,2]), end=max(treetest[,2])  ) ;
	     test5<-match(treetest[,2],c(tsp(treetemp)[1]:tsp(treetemp)[2]))     
	     treetemp[test5]<-treetest[,4] ;
	     recon<-ts.union(recon,treetemp);
	     name<-c(name,j)
	     }
	  }
	dimnames(recon)[[2]]<-  sub(" +$", "", levels(treef)[name])#removes trailing blanks
	collate<-recon
	collate
	} 

#treecalc
   treecalc<-function(url,long=FALSE,skip0=3) {
	treecalc<-make.rwl(url,long=FALSE,skip0=3) 
	trecalc}
	#this is just a change of name to reconcile with older scripts


#note: this includes some quality control checking on NGDC data - 
#the tag verify2 keeps track of few negative values, of which there are a few
#the tag start0 and end0 keeps track of start-dates and end-dates.  
#some "floating series" intentionally have start-dates way into the future
#a couple of series had RES as well as STD series and the RES data was manually deleted
#these entries are not relevant to the MBH subsets
# see script "ngdc.qc"
##make.chron.are
   make.chron.ars<-function(loc.in) {
	h<-readLines(loc.in,n=-1)
	start0<-as.numeric(substr(h[2],13,18))
	length0<-as.numeric(substr(h[2],4,8))
	h<-h[3:length(h)]
	fred<-as.numeric (substr(h,22,24))
	N<-length(h)
	test<-c(1:N)[is.na(fred)] #this looks for first alphanumeric header
	h<-h[1:(min(test)-1)] 
	write.table(h,file="d:/temp/h.txt",row.names=FALSE,quote=FALSE)
	g<-read.fwf("d:/temp/h.txt",skip=1, widths=rep( c(4,2),13))
	g<-g[,seq(1,25,2)]
	g<-c(t(g))
	make.chron.ars<-ts(g,start=start0,end=start0+length0-1)
	make.chron.ars
	}

### update details

	update.details<-function(loc,url0="ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/measurements") {
	if(!(url0=="ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/updates")) url0<-file.path(url0,countrycode(loc))	
	url<-file.path(url0,paste(loc,"rwl",sep="."))
 	h<-try(readLines(url,n=5))
	if (class(h)=="try-error") h<-readLines(file.path("ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/chronologies",countrycode(loc),paste(loc,"crn",sep=".")) ,n=5)
	dummy<-details[1,]
	dummy[1,]<-NA
	dummy$id<-loc
	dummy$location<-sub(" +$", "",substr(h[1],10,40))
	dummy$type<-substr(h[1],62,65)
	dummy$long<-as.numeric(substr(h[2],52,57))
	dummy$long<-dummy$long/100
	dummy$lat<-as.numeric(substr(h[2],47,51))
	dummy$lat<-dummy$lat/100
	dummy$altitude<-as.numeric(substr(h[2],41,44))
	dummy$altitude<-dummy$altitude
	dummy$start<-as.numeric(substr(h[2],67,71))
	dummy$start<-dummy$start
	dummy$end<-as.numeric(substr(h[2],72,76))
	dummy$end<-dummy$end
	dummy$author<-sub(" +$", "",substr(h[3],10,50))
	update.details<-dummy
	update.details
	}


country.out<-function(id) {
        temp<-match(substr(id,1,4),country.list[,1])
        if(is.na(temp)) country.out<-"northamerica" else country.out<- country.list[temp,2]
	if ((substr(id,1,4)=="cana")|(substr(id,1,4)=="mexi")) country.out<-"northamerica"
        country.out
        }


##CHECK MEASUREMENT CODE

##make.rwl
     #this is a very old script and can probably be improved, 
     #it's been re-edited to post on internet and has not been checked yet against oddball formats
	#earlier edition was thoroughly checked
        # a few oddball formats need to be checked out
	#FUNCTION TO READ RWL FILE AND MAKE LONG-FORM VERSION
		#returns list # tree, #two verification lists
		#the parameter long adjusts format when dates are -1000AD are less
 make.rwl<-function(loc,long=FALSE,method="wdcp",skip0=3,url0="ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/measurements") {
	trailer.verify<- 999
	trailing.marker<- (-9999)
	if(!(url0=="ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/updates")&!(method=="local")) url0<-file.path(url0,countrycode(loc))	
	url<-file.path(url0,paste(loc,"rwl",sep="."))
 	h<-try(readLines(url,n=5))
	if (class(h)=="try-error") make.rwl<-NA else {
	if( substr(h[4],6,6)=="-") long<-TRUE
	#if (long) 
	widths0<- c(8,4,rep(6,10)) ##else widths0<- c(7,5,rep(6,10))

	test<-as.numeric(substr(h,9,12))
	skip0<-sum(is.na(test))
	#	if(!is.numeric(tree[2,4])) tree<-read.fwf(file=url,widths=c(7,6,rep(6,10)),fill=TRUE,skip=3,blank.lines.skip=TRUE)
		#usually FALSE
		#if(!is.numeric(tree[1,3])) tree<-read.fwf(file=url,widths=c(7,5,rep(6,10)),fill=TRUE,skip=4,blank.lines.skip=TRUE)
		#usually FALSE
		#if(!is.numeric(tree[1,3])) tree<-read.fwf(file=url,widths=c(7,5,rep(6,10)),fill=TRUE,skip=5,blank.lines.skip=TRUE)
		#usually FALSE

	tree<-read.fwf(file=url,widths=widths0,fill=TRUE,skip=skip0,blank.lines.skip=TRUE) 
		#slightly different format when long
	if(class(tree[,2])=="factor") {widths0<- c(8,4,rep(6,10));   tree<-read.fwf(file=url,widths=widths0,fill=TRUE,skip=skip0,blank.lines.skip=TRUE) }
	tree[,1]<-factor(tree[,1])
	levels(tree[,1])<-sub(" +$", "",levels(tree[,1]));

       #check for oddball input formats
	temp<-is.na(tree[,1])  #typically 0 and next segment is not invoked
	if(sum(temp)>0) tree<-tree[!temp,]
	#   if (sum(temp)>1)  {h<-readLines(url);
	 #       h<-h[!temp]; 
	  #   	write.table(h,file="d:/temp/tree.txt",quote=FALSE,col.names=FALSE,row.names=FALSE);
	   #  	tree<-read.fwf(file="d:/temp/tree.txt",widths=c(8,4,rep(6,10)),fill=TRUE,skip=3,blank.lines.skip=TRUE)
	    # 	} #tests for oddball format
	#class(tree$V4)<-"numeric"  #change from integer
	#tree<-tree[!is.na(tree[,1]),] #remove NA values in ID if any; usually not

	test3=sapply(tree,class)[2:12]; 
	if (sum(!is.na(match(test3,"factor")))>0) {
	  fred=readLines(url); fred=fred[!(fred=="")];
	  fred=fred[4:length(fred)];  n=nchar(fred);treeid=substr(fred,1,8);treeid=gsub(" +$","",treeid)
	  fred=substr(fred,9,n)
	  fred=gsub("-9999"," -99 ",fred)
	  write.table(fred,"temp.dat",quote=FALSE,row.names=FALSE,col.names=FALSE)
	  tree=read.table("temp.dat",fill=TRUE)
	  tree[tree== -99]= -9999
          tree=data.frame(treeid,tree)
         }

      #check for trailing 999 markers; very annoying; also -9999 trailers
	n<-nrow(tree)
	temp.marker<-(tree[2:n,1]==tree[1:(n-1),1])
	temp.marker<-c(temp.marker,FALSE)
	temp.marker<-!temp.marker

	test1<- apply( tree[temp.marker,3:12],1,min,na.rm=TRUE)
	temp.trailer1<- (test1== -9999)
	id1<-tree[temp.marker,1][temp.trailer1]

	test2<- apply( tree[temp.marker,3:12],1,max,na.rm=TRUE)
	temp.trailer2<- (test2== 999)
	id2<-tree[temp.marker,1][temp.trailer2]

	temp.trailer<- ((tree[temp.marker,3:12]==999)|(tree[temp.marker,3:12]== -9999))   &!is.na(tree[temp.marker,3:12])
	tree[temp.marker,3:12][temp.trailer]<-NA #usually results in substitutions

      ##IF MIXED
	if ( (sum(temp.trailer1)>0) & (sum(temp.trailer2)>0) ) trailer.verify<-0
	if ( !(sum(temp.trailer1)>0) & (sum(temp.trailer2)>0) ) trailer.verify<-0
	print(paste(loc,trailer.verify))

	if (trailer.verify ==0) {
		temp<- !is.na(match( tree[,1], id2))	
        	tree[temp,3:12]<-10* tree[temp,3:12]}   

      ###   
	m<-length(levels(tree[,1]))
	tree<-cbind(tree,c(rep(0,n))) #make dummy column

	line.tree.no<-match(tree[,1],levels(tree[,1])) #this is index for tree
	year.start<-tapply(tree[,2],tree[,1],min) #NOTE: this doesn't work if ID is 8-digits (nv514)
	line.start<-year.start[line.tree.no]  #this gives v- vector
	tree[,13]<-line.start
	#tree<-cbind(tree[gl(n,1,10*n),1],tree[gl(n,1,10*n),2],tree[gl(n,1,10*n),13],stack(tree[1:nrow(tree),3:12])[,1] );##reshapes NGDC to long form
	tree<-data.frame(tree[gl(n,1,10*n),1],tree[gl(n,1,10*n),2],tree[gl(n,1,10*n),13],stack(tree[1:nrow(tree),3:12])[,1] );##reshapes NGDC to long form

	temp2<-t(array(rep(1:10,n),dim=c(10,n)));
	tree<-cbind(tree,c(temp2));##sets tag for column of NGDC entry to add back in long format 
		#reshape into long format with dim = n*10 x 9 #one column keeps indicator for potential reconstruction
		#id<-as.character(tree[,1])#scrapped

	tree<-data.frame(tree[,1],tree[,2]+tree[,5]-1,tree[,2]+tree[,5]-tree[,3],tree[,4]); 
	dimnames(tree)[[2]]<-c("id","year","age","rw")

     #use NA removal to remove trailing values on first and last records, but not missing values with na.marker
	temp<-!is.na(tree[,4]) 
	tree<-tree[temp,];
      #set negative values as NA
	temp<-(tree[,4]<0)
	if (sum(temp)>0) { verify<-tree[temp,];
		temp1<- (verify[,4] == -999);
		verify.NA<-verify[temp1,]; 
		verify.negative<-verify[!temp1,];
		tree[temp,4]<-NA }  else {verify.NA <-NULL;
		verify.negative<-NULL }
	
	#order by tree and by year
	order.tree<-order(tree[,1],tree[,2]);
	make.rwl<-tree[order.tree,];
	#possibly put into dataframe and edit column names
	}
	make.rwl
	}

	#tree<-make.rwl("russ022w")

  check.rwl<-function(loc,long=FALSE,skip0=3,url0="ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/measurements") {
	trailer.verify<- 999
	trailing.marker<- (-9999)
	if(!(url0=="ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/updates")) url0<-file.path(url0,countrycode(loc))	
	url<-file.path(url0,paste(loc,"rwl",sep="."))
	h<-try(readLines(url,n=5))
	if (class(h)=="try-error") check.rwl<-NA else {	
	if( substr(h[4],6,6)=="-") long<-TRUE
	#if (long) 
	widths0<- c(8,4,rep(6,10)) ##else widths0<- c(7,5,rep(6,10))

	test<-as.numeric(substr(h,9,12))
	skip0<-sum(is.na(test))
	#	if(!is.numeric(tree[2,4])) tree<-read.fwf(file=url,widths=c(7,6,rep(6,10)),fill=TRUE,skip=3,blank.lines.skip=TRUE)
		#usually FALSE
		#if(!is.numeric(tree[1,3])) tree<-read.fwf(file=url,widths=c(7,5,rep(6,10)),fill=TRUE,skip=4,blank.lines.skip=TRUE)
		#usually FALSE
		#if(!is.numeric(tree[1,3])) tree<-read.fwf(file=url,widths=c(7,5,rep(6,10)),fill=TRUE,skip=5,blank.lines.skip=TRUE)
		#usually FALSE

	tree<-read.fwf(file=url,widths=widths0,fill=TRUE,skip=skip0,blank.lines.skip=TRUE) 
		#slightly different format when long
	if(class(tree[,2])=="factor") {widths0<- c(8,4,rep(6,10));   tree<-read.fwf(file=url,widths=widths0,fill=TRUE,skip=skip0,blank.lines.skip=TRUE) }
	tree[,1]<-factor(tree[,1])
	levels(tree[,1])<-sub(" +$", "",levels(tree[,1]));

       #check for oddball input formats
	temp<-is.na(tree[,1])  #typically 0 and next segment is not invoked
	if(sum(temp)>0) tree<-tree[!temp,]

      #check for trailing 999 markers; very annoying; also -9999 trailers
	n<-nrow(tree)
	temp.marker<-(tree[2:n,1]==tree[1:(n-1),1])
	temp.marker<-c(temp.marker,FALSE)
	temp.marker<-!temp.marker

	test1<- apply( tree[temp.marker,3:12],1,min,na.rm=TRUE)
	temp.trailer1<- (test1== -9999)
	id1<-tree[temp.marker,1][temp.trailer1]

	test2<- apply( tree[temp.marker,3:12],1,max,na.rm=TRUE)
	temp.trailer2<- (test2== 999)
	id2<-tree[temp.marker,1][temp.trailer2]

	temp.trailer<- ((tree[temp.marker,3:12]==999)|(tree[temp.marker,3:12]== -9999))   &!is.na(tree[temp.marker,3:12])
	tree[temp.marker,3:12][temp.trailer]<-NA #usually results in substitutions

      ##IF MIXED
	if ( (sum(temp.trailer1)>0) & (sum(temp.trailer2)>0) ) trailer.verify<-0
	if ( !(sum(temp.trailer1)>0) & (sum(temp.trailer2)>0) ) trailer.verify<-0
	check.rwl<-trailer.verify
	}
	check.rwl
	}