STAG accepts one type of user input and produces four types of output files.

The input file recognized by STAG is:

  (1) a CACTOS stand description file (Wensel, Daugherty and Meerschaert,1986)
      that may be complete, or incomplete in one or more items discussed in 
      detail under Section II.A.

The primary output file created by STAG is :
  
  (1) a completed stand description file for use with the CACTOS individual 
      tree growth simulation system.

Other output files which may be created by STAG include:

  (2) externally saved stand description files, created by the es command, and
      used to save copies for later use of the stand description at the time the es 
      command was invoked  (optional).

  (3) report files are created with the rp command and are used to save
      information selected by the user during the course of the simulation 
      (optional). The report commands are discussed in section II.B. and IV.D.

  (4) a file containing height coefficients which are updated using local data
      (optional)


All input and output files are referenced by file names chosen by the user. 
STAG allows up to 32 characters for a file name. The computer system you use 
may mandate different limits on file name lengths. Individual systems may 
support the use of path names as part of the file name.

The authors recommend adoption of a naming convention that gives each file name
a root and an ending. The root indicates the stand being processed and the ending 
indicates the stand being processed and the ending indicates the type of file.
Root names are at the discretion of the user, but they should have a meaningful
pattern developed to fit the application. In the examples that follow, the 
suffixes serve the function of indicating the process that was used in STAG to 
complete the stand description file.

  .sd    stand description file
 
  .sda   stand description created in STAG using the distributional apportionment
         process for converting stand table data to complete individual tree 
         records

  .sdm   stand description which utilized the missing data routines of STAG to 
         estimate missing values to complete individual tree records

  .sdg   stand description created in STAG using the stand generation routines 
         to generate complete individual tree records

  .sdu   stand description created in STAG using the understory generation 
         routines

  .sdq   stand description created in STAG using a dimunition quotient to create 
         a negative exponential diameter distribution

  .srp   STAG report file

STAG has special filenames that are reserved and should be avoided by the user.
These include: "exp1", "exp2", and "stbin". These reserved filenames are used for 
storing values used in stand generation and foe storing user configuration 
parameters. Overwriting these files will prevent STAG from working properly.

Standard FORTRAN notation is provided here to described the format of each line
of input and output. Real numbers are expressed in the form rFw.d where w is the 
field width (total number of characters including blamks and decimal); d is the 
number of characters to the right of the decimal; and r is the number of times
this format is repeated by this specified by d in Fw.d. Thus, the format 5F8.3 
specifies 5 real numbers 8 characters wide with 3 places to the right of the 
decimal. Integer formats are of the form rIw, where w is the field width and r
is the repeater. Character formats are of the form rAw, where w is the number 
of characters in the field and r is the repeater.



II.A. Stand description input file   

STAG operates on stand description input files to accomplish any or all of the 
three objectives discussed in section III. A complete stand description input 
file must have the structure listed below, but an incomplete stand description 
may have missing values for total height and/or live crown ratio.

When working with stand table data the structure of the stand description is 
similar to that of a description file comprised of individual trees. However,
in this case, the diameter entry represents the diameter class midpoint usually
expressed in an integer value such as 12 or 14. Values for total height and live 
crown ratio are not required to form a description based upon these stand table
data. See Table 1 for a summary of the data requirements for the stand description 
files when there is missing data and for converting stand table data. See 
Appendix A for an example of a stand description file.

   Line(1) 	Stand description label, tree record count,elevation, and a 
 		number which indicates the file type (format A20, I10, I9, I9X, 
 		I3). These file type indicators are shown here:

		code	meaning
		0 or 1  raw data file with all heights measured in feet to the 
			tip of the tree
		2	heights are in feet to the merchantable top
		3	heights are in 16.5 foot logs above a 1.5 foot stump
		4  	heights are in 1/2 logs above a 1.5 foot stump
   
   Line(2)	Fifty year site indices for (in this order) ponderosa pine, 
		sugar pine, incense cedar, Douglas-fir, white fir, red fir, 
		lodgepole pine, white pine, Jeffrey pine,miscellaneous conifer,
		chinquapin, black oak, and miscellaneous hardwoods (format 
		14F5.0). STAG does not use site index in any of its functions, 
		but CACTOS uses site index extensively, therefore it must be 
		entered for every species present. Zeros or blanks may be 
 		entered for species not present on the plot.

   Line(3)	Breast height ages for (in this order) ponderosa pine, incense 
		cedar, Douglas-fir, white fir, red fir, lodgepole pine, Jeffrey 
		pine, miscellaneous conifer, chinquapin, black oak, tan oak, 
		and miscellaneous hardwood (format 14F5.0). Zeroes or blanks 
		may be entered if actual values are unknown. (Age is a 
		descriptive variable used in CACTOS only and is not needed for
		any of the models to function in either CACTOS or STAG.)

   Line(4)      Individual tree records follow, one per line. Each tree record
   		should have the five items listed in Table 1 (format 5F8.3, 
		i.e., one line for each tree record).

Table 1. Structure of stand description files for individual trees and for 
         stand tables.

 Stand description using individual      Stand description using stand table 
       tree                                    data
 (1) species code (see Table 2)           (1) species code (see Table 2)
 (2) DBH in inches  			  (2) diameter class midpoint
 (3) total height in feet (optional)      (3) average total height in feet 
                                              of trees in the diameter class 
                                              (optional)
 (4) live crown ratio in decimal          (4) live crown ratio in decimal 
     fraction (optional)                      fraction (optional)
 (5) pre-acre expansion factor            (5) per-acre expansion factor


Fourteen soecies are recognized by STAG on input. These species are listed
in Table 2.

Table 2. Species codes and names using in STAG.

Species                             Species
Code    Common Name              Abbreviation  Scientific Name
01	ponderosa pine                PP	Pinus ponderosa (Laws.)
02	sugar pine                    SP	Pinus lambertiana (Dougl.)
03	incense cedar                 IC	Libocedrus decurrens (Torr.)
04	Douglas-fir                   DF	Pseudotsuga menziesii (Mirb.) Franco
05	white fir                     WF	Abies concolor (Gorf. and Glend.) Lindl.
06	red fir                       RF	Abies magnifica (A. Murr.)
07	lodgepole pine                LP	Pinus contorta (Dougl.)
08	white pine                    WP	Pinus monticola (Dougl.)
09	Jeffrey pine                  JP	Pinus jeffreyi (Grev. & Balf.)
10	miscellaneous conifer         MC	n.a.
11	chinquapin                    CO	Castanopsis chrysophylla (Dougl.) A. DC.
12	black oak                     BO	Quercus kelloggii (Newb.)
13	tan oak                       TO	Lithocarpus densiflorus (Hook. & Arn.)
14	miscellaneous hardwood        MH	n.a.

These species are grouped into 8 different species groups during the 
simulation process. These groups are listed in Table 3.

Table 3. Species groups used for modelling in STAG.

Sp. Group  Species Croup   Species Group  Species Abbreviations and Codes
Code       Name            Abbreviation   Included in Group (See Table 2)
1	   Ponderosa Pine       PP	  PP(01), JP(09), LP(07) 
2	   Sugar Pine           SP	  SP(02), WP(08)
3	   Incense Cedar        IC	  IC(03)
4	   Douglas-fir          DF	  DF(04), MC(10)
5	   White Fir            WF	  WF(05)
6	   Red Fir              RF	  RF(06)
7	   Other Hardwoods	OH*       CH(11), TO(13), MH(14)
8	   Black Oak            BO        BO(12)

* Other hardwoods includes all hardwoods except black oak. However, the  
  equations were derived mainly from chiquapin and tanbark oak.

II.B. Report File

In addition to the completed stand description files, one or more report 
file(s) may be generated by the user while inside any of the main STAG 
functions except the configuration routine. The report file provides the user
with a mean of saving information which describes, or summarizes the 
characteristics of the trees contained in the stand description file. Many of 
the important report commands contained in CACTOS have been incorporated into
STAG. These include the following commands (described in detail in Section
IV.D):

  Command    Description
   pf	     graphs the stand profile of the trees in the stand description
   dt        graphs the diameter distribution of the trees in the stand 
	     description
   st        produces stock tables for the trees in the stand description

The report file is opened with the rp command. Any number of report files 
can be used during the course of a simulation, but only one may be open at 
a time. Reports can be saved in the report file by adding the argument o=r
or o=b to the command used to generate the report (see section IV).

II.C. Updated Height Coefficient File

While in the missing data routine (md), you are able to update the 
coefficients of the height models (Biging and others, 1991) using either a
pseudo-Bayesian or an adhoc technique for use on either the current stand 
descriptions or on others at a later time (see section III.A.). To use the
updated coefficients at a later time, you must place them in a special file
recognized bt STAG for this purpose. This can be accomplished by use of the 
update height coefficient command (uh) discussed in section IV.D. This file 
is a binary sequentially accessed file and is written and read by STAG very 
quickly.