Minor bug fixes and changes are not listed.
Users (+country code) who suggested changes are shown in brackets.

R43 (20 June 2012)
Scatter objects resolution improved to 0.1m (Wills.UK)

R42 (20 January 2010)
Updated with more efficient code to run with DosBOX

R41 (20 September 2006)
Scale on Approach can be toggled Threshold - Antenna <Perin-AU>

R40 (20 September 2005)
Default RDH can be saved as used determined values (Andreas-CH)
Sensitive Area readout and file print of data (Bakken-NO)
Table in Window OverWiev can be set to desired AZ angles (Hromadka-DE)

R39 (20 August 2003)
Changed step values for certain fields on the Control Panel
Bug fix in Near Field reading when having a reflection object
Bug fix in FWD SHIFT data for Null Ref and Sideband Ref (Maude-UK)
Bug fix in Sensitive Area when Track A-X was selected (Hicham-CAN)
Near Field monitor readings added to the Control Panel
Inner Half Sector readings (75uA) added to graphs (M.Wills-UK)
Scale on Approach now shows distance from Threshold (M.Wills-UK)

R38 (20 March 2002)
Run mode settings stored with model files (Daemen-NL)

R37 (20 November 2001)
Integral Monitor green status fields turn red at alarm set with Alt-X
Better control over Integral Monitor (MCU) manual settings

R36 (17 April 2000)
Bug fix in ADU module when switching on/off A1 and A3
FWD shift data from FSL given relative to A1 (P.Hatia-Black-UK)
/VOL argument for flight inspection mode Type 1 ADU (Spitz-F)
/FLIGHT argument for flight inspection mode Type 3 ADU (Spitz-F)

R35 (03 March 1999)
Alarm limits can be set on all three MCU output channels
MCU outputs DDM/CDI for GP angle, DS and Clearance simultaneously
Corrected SBO/CSB phase reading for cursor (Hooijenga-NL)
Alt-Y enables user to adjust ground plane Epsilon r and Conductivity

R34 (03 December 1998)
Cursor stretched to mark the entire vertical scale (T.Brown-UK)
Approach cursor measure distance both from Antenna & THR (Spanner-UK)
(F9)key in Approach shows bend amplitudes in Zone 2&3 (Bender-D)
Localiser Course Sector marked in Window Diagram (T.Brown-UK)

R32 (24 June 1998)
Toggle CLR ON/OFF by Alt-C will re-compute graphs directly (Lovhaug-N)
Phasing Cable Stub inserts in CSB/SBO/Remove by Alt-F2/F3/F4
Rx filter (rad/s) can be temporary set in Approach mode

R31 (20 March 1998)
Approach mode with new option for amplitudes along run (Greving-D)

R30 (20 October 1997)
RTS values monitored if adjusted directly in ADU fields (Spitz-F)
Corrected offset of curves when using %DDM
Clearance adjustments will not change lower screen data
Corrected Clearance signal independent of SBO level (Spitz-F)
Approach Level Run with angle readout w/cursor (Spitz-F)
New labelling of F-keys in all modes

R29 (04 May 1997)
Fixed Position Mode cursor & 90Hz sense activated on curves (Spitz-F)
Approach Mode automatic scale center function removed (Spitz-F)

R28 (20 March 1997)
Corrected sign errors in some curves
Antenna error settings independent of ADU feed readings (Aslaksen-N)

R27 (20 November 1995)
Two receiver selections for Capture Effect computations
Bug-Fix: Capture effect in DDM mode was 15% too low from CLR TX
Multiple Vertical Traces with separate forward/sideways distances
(1) adds -90deg and (9) adds +90deg in SBO from modulator
Two MCU channels (GP, Sector and DS) in Control Panel

R26 (31 March 1995)
Corrected remaining DATA when loading library files (F7) (Spitz-F)
Save most run-mode settings & toggles in setup mode (F3)
Alt-F2 Will copy scatter objects in "F8-Scatter Editor"
Workfile & Saved Screens directories easier to administrate
Scatter object made of several sheets can be offset as one unit
Corrected computation of clearance signal scatter from objects

R25 (20 March 1994)
Window diagram includes the ICAO specified 190uA (0.22ddm) line
SCATT.GB file contains a number of models for scattering objects
Scatter phase computation modified for certain sheet orientations

R24 (20 December 1993)
Bug-Fix: Window lines were too close in DDM mode (Nyback-N)
CDI/DDM and Meters/Feet selections added to default setup.
Bug-Fix: Mod Balance adjustments and MCU readout corrected
Adjustments in some antenna element radiation diagrams (Breien-N)
10 show directories accessible under Mode 1 for storing screens
10 work directories accessible under (F7) for storing models

R23 (20 September 93)
Software purified after reports on small bugs
Scatter objects picked by F2 through F6 keys instead of G, T, etc

R22 (20 August 1993)
Overwrite protection if attempting to save an existing file name
(F6)key enables Excel readable output file in Table output mode
Height scale option in Vertical Trace when Fwd dist < 1500m

R21 (05 August 1993)
Approach distance scale may be shown in meters, feet and NM.
Scatter objects may be loaded from a list in the SCATT.LST file
Most Character-key functions (L)oad (S)ave etc changed to F-keys
Multi language version. All texts are loaded from disk files.

Beta 20 (20 June 1993): [Version AXIS 330]
Optional Bend Limits for Cat I, II or III on Approach graph
Wire sections can be simulated as scattering object
Alt-D toggles readings and curves between %DDM and æA (Wipf-CH)
CDI sense may be reversed in Lateral and Vertical trace.
Approach distance scale may be shown in Nautical Miles
Printout can be set for printers with Roman8 character set.
Set aircraft speed and receiver/plotter response (Rchardt-D)
Library files are selected with cursor keys (Rchardt-D)
Toggle panels in each Mode for faster selections (Bastman-SF)
Sensitive Area mapped for CAT I, II and III on given conditions.
New modular format on saved files for better grouping of DATA.
Reflection sheet can be lifted from ground level and tilted.
New scatter integration algorithm for upto 16 simultaneous sheets
based on the Fresnel-Kirchhoff diffraction integral for
computation of reflection, diffraction and shadowing.
Ridge in terrain can be simulated as reflection object
Full scale deflection range expanded to ñ6 - ñ800æA
Move cursor between amplitude curves with up/down keys.
Move cursor along curves with left/right keys in Mode 3 and 5

The following are for AXIS versions 310-311-312 and earlier.
R19 (12 March 1993):
Some Hot-keys changed from one-key to Alt-keys.
AltM Toggles Antenna measures and distances between meters and feet
Setup entry for Printers with Roman8 character set.
Bug fix Fatal error when running graphics on CGA/HGA (Busto-E)
Replay speed can be adjusted by ñ keys (Ala-Mello-SF)
Graphic Colours can be user edited in the IGP.009 file
Cursor remains in last position when returning to Control Panel &
Ground Current (Mode 7) graph with expanded scale (Lenquette-F)
S key toggles ground slopes FSL & SSL between ø and % (Rchard-D)
Files library directory may be selected by user (Rchard-D)

á18 (05 December 1991):
Lateral trace ñ12øazimuth angle in Mode 3 (Brown-GB)
Right-Left arrow keys show values on Vertical-graph (Oedelien-N)
SSL impact on Threshold distance with /THR switch (Rchard-D)
C key toggles nominal Clearance amplitude ON/OFF

á17 (24 August 1991):
Direction may be reversed in Approach mode (Nilsson/Strandh-S)
B Key toggles between Black & White and Colours (Berglund-N)
Default settings in Runmodes initiated from IGP.004 file.
Negate, save, load and replay graphic screens (Brown-GB)

á16 (17 March 1991): [Version AXIS 312]
Capture effect computed by multiple Fourier instead of Butterworth
Hot keys de-activated when not in Control Panel (Bastman-SF)
SSL impact on Threshold distance removed (Vidal-F)
L Key locks lower screen data for upper screen entry (several)
Library files generated in a more stringent format
Modulator Mod.Bal (BAL) and SDM (Nominal 80%) can be adjusted.

á15 (14 January 1991):
Vertical trace may use multiple runs on same diagram (Dullaart-NL)
Re-entry of Licence number required when updating to á15.
SSL compensation added for THR dist./removed in Vertical Mode.
Slight changes in reflection plane properties (Bakken-N)
Bug fix for erratic ground reflection in latest á (Jorlet-DK)

á14 (23 October 1990):
Bug fix for one decade less impact of ADU phase (Busto-E)
Bug fix for one decade less impact of Azimuth turn (Breien-N)
Get/Save file for user defined values in Mode 3, 4 & 5 (Jorlet-DK)
Bug fix for erratic Bend computation & analyzing (Busto-E)
Bug fix for double errors in feeds at printout (Busto-E)
Optimized feeds listed for all objects at F8key (Halkola-SF)

á13 (22 August 1990):
Either height(m) or angle(ø) entry at Optimizing (Halkola-SF)
Window diagram includes computed angles and sectors.
MCU module (F4-key) has menu for pre-selected angles.
DD Hot-key toggles Control Panel readings %DDM and æA (V„re-SF)
Graphic presentation added to R-key FSL computation (Krosby-N)
Bug fix for SBO attenuator causing antenna feeds perturbation.
Resolution one decade better for all feed parameters.

á12 (12 August 1990): [Version AXIS 311]
FSL and SSL resolution increased to 1/1000ø (Berglund-N)
R-key FSL computation may enter any distance/height (Krosby-N)
Help key for reflection factor when entering objects (Breien-N)
Optimized coordinates displayed on Control Panel (Breien-N)
Corrected failure to find best screen at first registration.
MCU settings added to the library files content
Type 'EXIT' prompt always on as a reminder while SHELL to DOS
Library files generated in a more readable format
More exact near field monitor location computed (Krosby-N)

á11 (02 August 1990):
Ground current for SBO, CSB and CLR signals separately.
Optimize directly on any of the listed reflection objects.
Improved error handling (Krosby-N)
(G)raphics or (S)cale direct at all Menu options (Antila-SF)

á10 (17 July 1990):
ADU adjustments enabled for M & SBR, MCU for all GP types.
MCU output & attenuators can be set by F4key (Nyback-N)
Both UTD input & data files are generated by AXIS 310 (Bakken-N)
DB Hot-key toggles all Lower screen amplitudes dB/% (Krosby-N)

á09 (11 July 1990):
/THEO argument enables theodolite upward tilt (Schwendener-CH).
Correction in Ground Current when FSL were sloping

á08 (09 June 1990):
Improved Computation of Sectors in Vertical & Level modes
Amplitude graphs for SBO & CSB in Fixed Position Mode (Nyback-N).
Re-entry of Licence number required when updating to á8 or
later versions.

á07 (02 May 1990):
Better HERCULES Screen handling (Van Noort-NL)
Colours can only be set in F3-key Mode (Schwendener-CH)
7-key for colour control for screen text
General improvements and cosmetical changes in most modes

á06 (17 April 1990):
If UTD is present, UTD menus appear where applicable
Enabled Hardcopy printout of Tables (Krosby-N)

á05 (19. february 1990):
Amplitude graphs for SBO & CSB in 2D Vertical Trace
Threshold Crossing & Height DATA fields on Control Panel (Breien-N)
Correction in Actual GP angle & DATUM height computation

á04 (01. february 1990):
Selectable Low/High Amplitude range in SBO/CSB Window
/CGA argument forces the Screen mode to CGA screen ,Type 2
/HERC argument forces the Screen mode to HERCULES ,Type 3
/EGA argument forces the Screen mode to EGA screen ,Type 9
/VGA argument forces the Screen mode to VGA screen ,Type 12
/SCREEN argument finds best screen mode. Intended for NetWork
/AIR argument makes Window seen from the Air by Default (Jorlet-DK)
Alt-P (Alt-L) prints Screen on LPT2. For NetWork (Nilsson-S)
Computes Actual & Achieved GP/DATUM heights on Approaches (Breien-N)
R Hot-Key makes Quick Computation of Reflection Plane slope
0 Hot-Key zero out Offset or Fwd Tilt Data Fields
Added Very High resolution in Window Diagram. 4 levels now.
Corrected Azimuth diagram for NM and Kathrein antennas (Jordet-N)
Complete GP Model Setup information at Graphics printout (Captyn-DK)
Finds best screen mode at first time registration. (Jorlet-DK)
C Hot-Key chops clearance signal during Vert, Appr and Fixed.
Changed GP model from linear to curved along the earth (Jorlet-DK)
Corrected Ant Azimuth radiation for GP on Left Hand side (Jordet-N)

á03 (02. january 1990):
Multiple split graphics in Vertical 3D mode.
Convert "," to decimal point "." for inputs on Num Pad (Jorlet-DK)
Corrected Bug of inverse response in ADU o/p Probes
Cleaned up Window Diagram SBO/CSB Amplitude Curves.
New Format in DATA entry file IGP.003 and File library

á02 (19. december 1989):
More GP Setup information at Graphics printout
Window can be seen either from the Ground or the Air (Jorlet-DK)
F10 key exits the program level by level (Garder-N)
Keyboard inhibited during Graphics Drawing (Captyn-DK)
NetWork Installation User Code only entered once (Nilsson-S)
RTS & RTC more accurate with one decimal on screen.
UTD can be run as Sub module in Approach and Vertical.

á01 (16. december 1989):
Snow Layers can be entered, viewed and modified by F9.
Window and Vertical 3D DATA interconnected by Menues.
Re-design of the Control Panel into 8 areas.

1990 : Named the software AXIS 510 as the continued version
of ILS GLIDEPATH SIMULATOR 5.1. Later renamed to 310
when localiser came as AXIS 110. AXIS means course line
in French and is a good short name for ILS software.

1989 : Started the writing of IGP 5.1 as a more advanced
version of IGP 5.0 having additional features intended for
a more specialized user group.
Rewritten for new compiler in structured language with
arrow keys/Mouse Data entry and simultaneous update of
all parameters on screen as ILS GLIDEPATH SIMULATOR 5.0
in Beta versions 1 - 42.

1987 : Improved versions correcting bugs as
versions 4.00 - 4.03 (Rgm/Xby).

1985 : Full Commodore 64 code converted to IBM PC as
version 3/Xby.

1984 : HP-BASIC versions converted and re-written for
Commodore 64 and IBM PC as version 2.4 and 2.5
for ILS Courses and demonstrations in public.

1983 : Ultra-compact releases 2.0 - 2.4 written for
Casio FX-702 and releases 7.0 - 7.9 for CASIO
PB-700. Main usage is portable field work and
advanced training courses in Image Glidepath.

1979 : Developed as an advanced versatile tool for
simulation of Image Glidepath behavior under
erronous operation and adverse environment.
Written in HP-BASIC on HP9845 Computer as
ILS 307, 308 and 309. Later on HP9845B as
versions GP1 (A - U) and then GP1 (Beta1 - 35)
in the time period 1979 - 1983.
Bend Analysis program written as GP5 (1 - 11).