This is one of the core programmes in SURPAC, as it the primary interface between the Surveyor's field work and the calculation and/or draughting applications within the software.

Data in an Observation File are required to be in the observation mode, viz :-

	Point Name
	Point Description Code
	Observation Code
	Horizontal Angle
	Vertical Angle (If 0°, 90°, 180° or 270°, then the Distance given must be the Horizontal Distance)
	Slope Distance
	Instrument Height
	Target Height

The Point Description Code is a simple value, 1 through 9, which allows the selected application to identify the function of each Data Line in the Observation file, and to apply the appropriate action. 

Data input into an Observation File is by either :-

	Direct Downloading from a Total Station or an Electronic Logger, The currently supported Total Stations and/or Electronic Loggers are :- The Psion Organiser using the "Handi-Data Solutions Booker Ver 5" software, The Psion Workabout, using the "Handi-Data Solutions Booker Ver 6" software,  The Leica/Wild GIF10 data logger,  The Leica TC 605/805/905 Series Total Station,  The Leica TCR 303/305/307 Series Total Station,  The Nikon DTM-400 Series Total Station,  The Nikon NPL-300/350/500/800 Series Total Station,  The Pentax PCS-300/R-300 Series Total Station,    The Pentax W-825NX Series Total Station, The Sokkia SET2C/SET3C Series Total Station,  The Sokkia SET2100/SET3100/SET4100 Series Total Station,  The Sokkia SET2110/SET3110/SET4110 Series Total Station,  The Sokkia SET300/ SET500/ SET600 Total Station,  The Topcon GTS-200/210 Series Total Station,  The Topcon GTS-500/700 Series Total Station. The Topcon GPT-3000 Series Total Station. The Topcon GPT-3100 Series Total Station.
	Downloading from a variety of ASCII file formats,
	Copying from the Windows Clipboard,
	Importing from another SURPAC Observation File, or
	by Manual Data entry.

The following SURPAC applications use data extraction from a User selected Observation File :-

	Mass Polar reductions, or individual Polar reductions,
	Reverse Polar reductions,
	"Two Sides and the included Angle" reductions,
	Tacheometric reductions,
	Field Traverse calculations,
	Least Squares Adjustment of Single Point Fixes [Y, X, Z] (or [E, N, H]),
	Least Squares Adjustment of [Y, X]  (or [E, N]) Networks,
	Least Squares Adjustment of Trigonometrical Height Networks,
	Mining "Double Set-Up" Peg Fixing,
	Mining "Double Button" Peg Fixing,
	Mining Off-Set (direct and/or indirect) reductions.

Once an Observation File has been generated, various editing/printing functions are available, such as :-

	Manually modifying, or Deleting, Data Lines,
	Using the Windows "Cut and Paste" to move blocks of Data around the File,
	Manually Adding or Inserting new Data Lines,
	Meaning multiple Point sightings within a Set Up,
	Auto-detecting any Code inconsistencies in the File,
	Applying a User selected factor to Distances and/or Target Heights,
	Changing the "Active" status for individual observations, or Set Ups. The "Active" status of a Data Line determines whether or not that Line is used in a called application,
	Printing the Observation File in "Raw" format,
	Printing the Observation File in "Field Book" format,
	Creating an ASCII file of the Data,
	Sending the Data to the Windows Clipboard.