Source Code

048282,000001: # Copyright: Public domain. 048283,000002: # Filename: PLANETARY_INERTIAL_ORIENTATION.agc 048284,000003: # Purpose: Part of the source code for Luminary 1A build 099. 048285,000004: # It is part of the source code for the Lunar Module's (LM) 048286,000005: # Apollo Guidance Computer (AGC), for Apollo 11. 048287,000006: 048288,000007: # Assembler: yaYUL 048289,000008: # Contact: Jim Lawton <jim.lawton@gmail.com> 048290,000009: # Website: www.ibiblio.org/apollo. 048291,000010: # Pages: 1140-1148 048292,000011: # Mod history: 2009-05-28 JVL Updated from page images. 048293,000012: 048294,000013: # This source code has been transcribed or otherwise adapted from digitized 048295,000014: # images of a hardcopy from the MIT Museum. The digitization was performed 048296,000015: # by Paul Fjeld, and arranged for by Deborah Douglas of the Museum. Many 048297,000016: # thanks to both. The images (with suitable reduction in storage size and 048298,000017: # consequent reduction in image quality as well) are available online at 048299,000018: # www.ibiblio.org/apollo. If for some reason you find that the images are 048300,000019: # illegible, contact me at info@sandroid.org about getting access to the 048301,000020: # (much) higher-quality images which Paul actually created. 048302,000021: 048303,000022: # Notations on the hardcopy document read, in part: 048304,000023: 048305,000024: # Assemble revision 001 of AGC program LMY99 by NASA 2021112-061 048306,000025: # 16:27 JULY 14, 1969 048307,000026: 048308,000027: # Page 1140 048309,000028: # ***** RP-TO-R SUBROUTINE ***** 048310,000029: # SUBROUTINE TO CONVERT RP (VECTOR IN PLANETARY COORDINATE SYSTEM, EITHER 048311,000030: # EARTH-FIXED OR MOON-FIXED) TO R (SAME VECTOR IN THE BASIC REF. SYSTEM) 048312,000031: 048313,000032: # R = MT(T) * (RP + LP X RP) MT = M MATRIX TRANSPOSE 048314,000033: 048315,000034: # CALLING SEQUENCE 048316,000035: # L CALL 048317,000036: # L+1 RP-TO-R 048318,000037: 048319,000038: # SUBROUTINES USED 048320,000039: # EARTHMX, MOONMX, EARTHL 048321,000040: 048322,000041: # ITEMS AVAILABLE FROM LAUNCH DATA 048323,000042: # 504LM = THE LIBRATION VECTOR L OF THE MOON AT TIME TIMSUBL, EXPRESSED 048324,000043: # IN THE MOON-FIXED COORD. SYSTEM RADIANS B0 048325,000044: 048326,000045: # ITEMS NECESSARY FOR SUBR. USED (SEE DESCRIPTION OF SUBR.) 048327,000046: 048328,000047: # INPUT 048329,000048: # MPAC = 0 FOR EARTH, NON-ZERO FOR MOON 048330,000049: # 0-5D = RP VECTOR 048331,000050: # 6-7D = TIME 048332,000051: 048333,000052: # OUTPUT 048334,000053: # MPAC = R VECTOR METERS B-29 FOR EARTH, B-27 FOR MOON 048335,000054: 048336,000055: 26,2000 SETLOC PLANTIN1 048337,000056: 26,2000 BANK 048338,000057: 048339,000058: 26,3716 COUNT* $$/LUROT 048340,000059: 048341,000060: 26,3716 46020 RP-TO-R STQ BHIZ 048342,000061: 26,3717 00050 RPREXIT 048343,000062: 26,3720 55733 RPTORA 048344,000063: 26,3721 77624 CALL # COMPUTE M MATRIX FOR MOON 048345,000064: 26,3722 51720 MOONMX # LP=LM FOR MOON RADIANS B0 048346,000065: 26,3723 77775 VLOAD 048347,000066: 26,3724 02013 504LM 048348,000067: 26,3725 53235 RPTORB VXV VAD 048349,000068: 26,3726 00001 504RPR 048350,000069: 26,3727 00001 504RPR 048351,000070: 26,3730 52105 VXM GOTO 048352,000071: 26,3731 00025 MMATRIX # MPAC=R=MT(T)*(RP+LPXRP) 048353,000072: 26,3732 51706 RPRPXXXX # RESET PUSHLOC TO 0 BEFORE EXITING 048354,000073: 26,3733 77624 RPTORA CALL # EARTH COMPUTATIONS 048355,000074: 26,3734 55743 EARTHMX # M MATRIX B-1 048356,000075: 26,3735 77624 CALL 048357,000076: 26,3736 15753 EARTHL # L VECTOR RADIANS B0 048358,000077: 26,3737 76521 MXV VSL1 # LP=M(T)*L RAD B-0 048359,000078: 26,3740 00025 MMATRIX 048360,000079: # Page 1141 048361,000080: 26,3741 77650 GOTO 048362,000081: 26,3742 55725 RPTORB 048363,000082: 24,2000 SETLOC PLANTIN 048364,000083: 24,2000 BANK 048365,000084: 24,3670 COUNT* $$/LUROT 048366,000085: 048367,000086: # Page 1142 048368,000087: # ***** R-TO-RP SUBROUTINE ***** 048369,000088: # SUBROUTINE TO CONVERT R (VECTOR IN REFERENCE COORD. SYSTEM) TO RP 048370,000089: # (VECTOR IN PLANETARY COORD SYSTEM) EITHER EARTH-FIXED OR MOON-FIXED 048371,000090: 048372,000091: # RP = M(T) * (R - L X R) 048373,000092: 048374,000093: # CALLING SEQUENCE 048375,000094: # L CALL 048376,000095: # L+1 R-TO-RP 048377,000096: 048378,000097: # SUBROUTINES USED 048379,000098: # EARTHMX, MOONMX, EARTHL 048380,000099: 048381,000100: # INPUT 048382,000101: # MPAC = 0 FOR EARTH, NON-ZERO FOR MOON 048383,000102: # 0-5D = R VECTOR 048384,000103: # 6-7D = TIME 048385,000104: 048386,000105: # ITEMS AVAILABLE FROM LAUNCH DATA 048387,000106: # 504LM = THE LIBRATION VECTOR L OF THE MOON AT TIME TIMSUBL, EXPRESSED 048388,000107: # IN THE MOON-FIXED COORD. SYSTEM RADIANS B0 048389,000108: 048390,000109: # ITEMS NECESSARY FOR SUBROUTINES USED (SEE DESCRIPTION OF SUBR.) 048391,000110: 048392,000111: # OUTPUT 048393,000112: # MPAC = RP VECTOR METERS B-29 FOR EARTH, B-27 FOR MOON 048394,000113: 048395,000114: 24,3670 46020 R-TO-RP STQ BHIZ 048396,000115: 24,3671 00050 RPREXIT 048397,000116: 24,3672 51712 RTORPA 048398,000117: 24,3673 77624 CALL 048399,000118: 24,3674 51720 MOONMX 048400,000119: 24,3675 61375 VLOAD VXM 048401,000120: 24,3676 02013 504LM # LP=LM 048402,000121: 24,3677 00025 MMATRIX 048403,000122: 24,3700 77772 VSL1 # L = MT(T)*LP RADIANS B0 048404,000123: 24,3701 51235 RTORPB VXV BVSU 048405,000124: 24,3702 00001 504RPR 048406,000125: 24,3703 00001 504RPR 048407,000126: 24,3704 77721 MXV # M(T)*(R-LXR) B-2 048408,000127: 24,3705 00025 MMATRIX 048409,000128: 24,3706 40372 RPRPXXXX VSL1 SETPD 048410,000129: 24,3707 00001 0D 048411,000130: 24,3710 77650 GOTO 048412,000131: 24,3711 00050 RPREXIT 048413,000132: 24,3712 77624 RTORPA CALL # EARTH COMPUTATIONS 048414,000133: 24,3713 55743 EARTHMX 048415,000134: 24,3714 77624 CALL 048416,000135: 24,3715 15753 EARTHL 048417,000136: 24,3716 77650 GOTO # MPAC=L=(-AX,-AY,0) RAD B-0 048418,000137: 24,3717 51701 RTORPB 048419,000138: 048420,000139: # Page 1143 048421,000140: # ***** MOONMX SUBROUTINE ***** 048422,000141: # SUBROUTINE TO COMPUTE THE TRANSFORMATION MATRIX M FOR THE MOON 048423,000142: 048424,000143: # CALLING SEQUENCE 048425,000144: # L CALL 048426,000145: # L+1 MOONMX 048427,000146: 048428,000147: # SUBROUTINES USED 048429,000148: # NEWANGLE 048430,000149: 048431,000150: # INPUT 048432,000151: # 6-7D = TIME 048433,000152: 048434,000153: # ITEMS AVAILABLE FROM LAUNCH DATA 048435,000154: # BSUBO, BDOT 048436,000155: # TIMSUBO, NODIO, NODDOT, FSUBO, FDOT 048437,000156: # COSI = COS(I) B-1 048438,000157: # SINI = SIN(I) B-1 048439,000158: # I IS THE ANGLE BETWEEN THE MEAN LUNAR EQUATORIAL PLANE AND THE 048440,000159: # PLANE OF THE ECLIPTIC (1 DEGREE 32.1 MINUTES) 048441,000160: 048442,000161: # OUTPUT 048443,000162: # MMATRIX = 3X3 M MATRIX B-1 (STORED IN VAC AREA) 048444,000163: 048445,000164: 24,3720 40220 MOONMX STQ SETPD 048446,000165: 24,3721 00051 EARTHMXX 048447,000166: 24,3722 00011 8D 048448,000167: 24,3723 77770 AXT,1 # B REQUIRES SL 0, SL 5 IN NEWANGLE 048449,000168: 24,3724 00005 5 048450,000169: 24,3725 65345 DLOAD PDDL # PD 10D 8-9D=BSUBO 048451,000170: 24,3726 14017 BSUBO # 10-11D=BDOT 048452,000171: 24,3727 14011 BDOT 048453,000172: 24,3730 45006 PUSH CALL # PD 12D 048454,000173: 24,3731 53743 NEWANGLE # EXIT WITH PD 8D AND MPAC= B REVS B0 048455,000174: 24,3732 71406 PUSH COS # PD 10D 048456,000175: 24,3733 14041 STODL COB # PD 8D COS(B) B-1 048457,000176: 24,3734 77756 SIN # SIN(B) B-1 048458,000177: 24,3735 14043 STODL SOB # SETUP INPUT FOR NEWANGLE 048459,000178: 24,3736 14015 FSUBO # 8-9D=FSUBO 048460,000179: 24,3737 41525 PDDL PUSH # PD 10D THEN 12D 10-11D=FDOT 048461,000180: 24,3740 14007 FDOT 048462,000181: 24,3741 45170 AXT,1 CALL # F REQUIRES SL 1, SL 6 IN NEWANGLE. 048463,000182: 24,3742 00004 4 048464,000183: 24,3743 53743 NEWANGLE # EXIT WITH PD 8D AND MPAC= F REVS B0 048465,000184: 24,3744 14027 STODL AVECTR +2 # SAVE F TEMP 048466,000185: 24,3745 14013 NODIO # 8-9D=NODIO 048467,000186: 24,3746 41525 PDDL PUSH # PD 10D THEN 12D 10-11D=NODDOT 048468,000187: 24,3747 14005 NODDOT # MPAC=T 048469,000188: 24,3750 45170 AXT,1 CALL # NODE REQUIRES SL 0, SL 5 IN NEWANGLE 048470,000189: 24,3751 00005 5 048471,000190: 24,3752 53743 NEWANGLE # EXIT WITH PD 8D AND MPAC= NODI REVS B0 048472,000191: # Page 1144 048473,000192: 24,3753 71406 PUSH COS # PD 10D 8-9D= NODI REVS B0 048474,000193: 24,3754 77606 PUSH # PD 12D 10-11D= COS(NODI) B-1 048475,000194: 24,3755 00025 STORE AVECTR 048476,000195: 24,3756 76405 DMP SL1R 048477,000196: 24,3757 00041 COB # COS(NODI) B-1 048478,000197: 24,3760 14035 STODL BVECTR +2 # PD 10D 20-25D=AVECTR= COB*SIN(NODI) 048479,000198: 24,3761 76405 DMP SL1R # SOB*SIN(NODI) 048480,000199: 24,3762 00043 SOB 048481,000200: 24,3763 14037 STODL BVECTR +4 # PD 8D 048482,000201: 24,3764 41556 SIN PUSH # PD 10D -SIN(NODI) B-1 048483,000202: 24,3765 77676 DCOMP # 26-31D=BVECTR= COB*COS(NODI) 048484,000203: 24,3766 14033 STODL BVECTR # PD 8D SOB*COS(NODI) 048485,000204: 24,3767 00027 AVECTR +2 # MOVE F FROM TEMP LOC. TO 504F 048486,000205: 24,3770 14007 STODL 504F 048487,000206: 24,3771 76405 DMP SL1R 048488,000207: 24,3772 00041 COB 048489,000208: 24,3773 77650 GOTO 048490,000209: 24,3774 53671 MOONMXA 048491,000210: 048492,000211: 25,3671 BANK 25 048493,000212: 25,2000 SETLOC PLANTIN3 048494,000213: 25,2000 BANK 048495,000214: 25,3671 COUNT* $$/LUROT 048496,000215: 048497,000216: 25,3671 14027 MOONMXA STODL AVECTR +2 048498,000217: 25,3672 00011 SINNODI # 8-9D=SIN(NODI) B-1 048499,000218: 25,3673 76405 DMP SL1R 048500,000219: 25,3674 00043 SOB 048501,000220: 25,3675 14031 STODL AVECTR +4 # 0 048502,000221: 25,3676 06522 HI6ZEROS # 8-13D= CVECTR= -SOB B-1 048503,000222: 25,3677 57525 PDDL DCOMP # PD 10D COB 048504,000223: 25,3700 00043 SOB 048505,000224: 25,3701 63325 PDDL PDVL # PD 12D THEN PD 14D 048506,000225: 25,3702 00041 COB 048507,000226: 25,3703 00033 BVECTR 048508,000227: 25,3704 63361 VXSC PDVL # PD 20D BVECTR*SINI B-2 048509,000228: 25,3705 14003 SINI 048510,000229: 25,3706 00011 CVECTR 048511,000230: 25,3707 53361 VXSC VAD # PD 14D CVECTR*COSI B-2 048512,000231: 25,3710 14001 COSI 048513,000232: 25,3711 77772 VSL1 048514,000233: 25,3712 24041 STOVL MMATRIX +12D # PD 8D M2=BVECTR*SINI+CVECTR*COSI B-1 048515,000234: 25,3713 63361 VXSC PDVL # PD 14D 048516,000235: 25,3714 14003 SINI # CVECTR*SINI B-2 048517,000236: 25,3715 00033 BVECTR 048518,000237: 25,3716 52361 VXSC VSU # PD 8D BVECTR*COSI B-2 048519,000238: 25,3717 14001 COSI 048520,000239: 25,3720 65372 VSL1 PDDL # PD 14D 048521,000240: 25,3721 00007 504F # 8-13D=DVECTR=BVECTR*COSI-CVECTR*SINI B-1 048522,000241: 25,3722 74346 COS VXSC 048523,000242: # Page 1145 048524,000243: 25,3723 00011 DVECTR 048525,000244: 25,3724 73525 PDDL SIN # PD 20D 14-19D= DVECTR*COSF B-2 048526,000245: 25,3725 00007 504F 048527,000246: 25,3726 52361 VXSC VSU # PD 14D AVECTR*SINF B-2 048528,000247: 25,3727 00025 AVECTR 048529,000248: 25,3730 77772 VSL1 048530,000249: 25,3731 14033 STODL MMATRIX +6 # M1= AVECTR*SINF-DVECTR*COSF B-1 048531,000250: 25,3732 00007 504F 048532,000251: 25,3733 74356 SIN VXSC # PD 8D 048533,000252: 25,3734 71525 PDDL COS # PD 14D 8-13D=DVECTR*SINF B-2 048534,000253: 25,3735 00007 504F 048535,000254: 25,3736 53361 VXSC VAD # PD 8D AVECTR*COSF B-2 048536,000255: 25,3737 00025 AVECTR 048537,000256: 25,3740 57572 VSL1 VCOMP 048538,000257: 25,3741 34025 STCALL MMATRIX # M0= -(AVECTR*COSF+DVECTR*SINF) B-1 048539,000258: 25,3742 00051 EARTHMXX 048540,000259: 048541,000260: # COMPUTE X=X0+(XDOT)(T+T0) 048542,000261: # 8-9D= X0 (REVS B-0), PUSHLOC SET AT 12D 048543,000262: # 10-11D=XDOT (REVS/CSEC) SCALED B+23 FOR WEARTH,B+28 FOR NODDOT AND BDOT 048544,000263: # AND B+27 FOR FDOT 048545,000264: # X1=DIFFERENCE IN 23 AND SCALING OF XDOT, =0 FOR WEARTH, 5 FOR NDDOT AND 048546,000265: # BDOT AND 4 FOR FDOT 048547,000266: # 6-7D=T (CSEC B-28), TIMSUBO= (CSEC B-42 TRIPLE PREC.) 048548,000267: 048549,000268: 25,3743 54345 NEWANGLE DLOAD SR # ENTER PD 12D 048550,000269: 25,3744 00007 6D 048551,000270: 25,3745 20617 14D 048552,000271: 25,3746 72371 TAD TLOAD # CHANGE MODE TO TP 048553,000272: 25,3747 01707 TIMSUBO 048554,000273: 25,3750 00155 MPAC 048555,000274: 25,3751 14017 STODL TIMSUBM # T+T0 CSEC B-42 048556,000275: 25,3752 00020 TIMSUBM +1 048557,000276: 25,3753 77605 DMP # PD 10D MULT BY XDOT IN 10-11D 048558,000277: 25,3754 43257 SL* DAD # PD 8D ADD X0 IN 8-9D AFTER SHIFTING 048559,000278: 25,3755 20206 5,1 # SUCH THAT SCALING IS B-0 048560,000279: 25,3756 67206 PUSH SLOAD # PD 10D SAVE PARTIAL (X0+XDOT*T) IN 8-9D 048561,000280: 25,3757 00017 TIMSUBM 048562,000281: 25,3760 41261 SL DMP 048563,000282: 25,3761 20212 9D 048564,000283: 25,3762 00013 10D # XDOT 048565,000284: 25,3763 43257 SL* DAD # PD 8D SHIFT SUCH THAT THIS PART OF X 048566,000285: 25,3764 20213 10D,1 # IS SCALED REVS/CSEC B-0 048567,000286: 25,3765 77600 BOV # TURN OFF OVERFLOW IF SET BY SHIFT 048568,000287: 25,3766 53767 +1 # INSTRUCTION BEFORE EXITING. 048569,000288: 25,3767 77616 RVQ # MPAC=X= X0+(XDOT)(T+T0) REVS B0 048570,000289: 048571,000290: # Page 1146 048572,000291: # ***** EARTHMX SUBROUTINE ***** 048573,000292: # SUBROUTINE TO COMPUTE THE TRANSFORMATION MATRIX M FOR THE EARTH 048574,000293: 048575,000294: # CALLING SEQUENCE 048576,000295: # L CALL 048577,000296: # L+1 EARTHMX 048578,000297: 048579,000298: # SUBROUTINE USED 048580,000299: # NEWANGLE 048581,000300: 048582,000301: # INPUT 048583,000302: # INPUT AVAILABLE FROM LAUNCH DATA AZO REVS B-0 048584,000303: # TEPHEM CSEC B-42 048585,000304: # 6-7D= TIME CSEC B-28 048586,000305: 048587,000306: # OUTPUT 048588,000307: # MMATRIX= 3X3 M MATRIX B-1 (STORED IN VAC AREA) 048589,000308: 048590,000309: 26,3743 BANK 26 048591,000310: 26,2000 SETLOC PLANTIN1 048592,000311: 26,2000 BANK 048593,000312: 26,3743 COUNT* $$/LUROT 048594,000313: 048595,000314: 26,3743 40220 EARTHMX STQ SETPD # SET 8-9D=AZO 048596,000315: 26,3744 00051 EARTHMXX 048597,000316: 26,3745 00011 8D # 10-11D=WEARTH 048598,000317: 26,3746 77770 AXT,1 # FOR SL 5, AND SL 10 IN NEWANGLE 048599,000318: 26,3747 00000 0 048600,000319: 26,3750 65345 DLOAD PDDL # LEAVING PD SET AT 12D FOR NEWANGLE 048601,000320: 26,3751 01712 AZO 048602,000321: 26,3752 14021 WEARTH 048603,000322: 26,3753 45006 PUSH CALL 048604,000323: 26,3754 53743 NEWANGLE 048605,000324: 26,3755 41401 SETPD PUSH # 18-19D=504AZ 048606,000325: 26,3756 00023 18D # COS(AZ) SIN(AZ) 0 048607,000326: 26,3757 65346 COS PDDL # 20-37D= MMATRIX= -SIN(AZ) COS(AZ) 0 B-1 048608,000327: 26,3760 00023 504AZ # 0 0 1 048609,000328: 26,3761 65356 SIN PDDL 048610,000329: 26,3762 06522 HI6ZEROS 048611,000330: 26,3763 73525 PDDL SIN 048612,000331: 26,3764 00023 504AZ 048613,000332: 26,3765 65276 DCOMP PDDL 048614,000333: 26,3766 00023 504AZ 048615,000334: 26,3767 63346 COS PDVL 048616,000335: 26,3770 06522 HI6ZEROS 048617,000336: 26,3771 41525 PDDL PUSH 048618,000337: 26,3772 06520 HIDPHALF 048619,000338: 26,3773 77650 GOTO 048620,000339: 26,3774 00051 EARTHMXX 048621,000340: 048622,000341: # Page 1147 048623,000342: # ***** EARTHL SUBROUTINE ***** 048624,000343: # SUBROUTINE TO COMPUTE L VECTOR FOR EARTH 048625,000344: 048626,000345: # CALLING SEQUENCE 048627,000346: # L CALL 048628,000347: # L+1 EARTHL 048629,000348: 048630,000349: # INPUT 048631,000350: # AXO,AYO SET AT LAUNCH TIME WITH AYO IMMEDIATELY FOLLOWING AXO IN CORE 048632,000351: 048633,000352: # OUTPUT 048634,000353: # -AX 048635,000354: # MPAC= -AY RADIANS B-0 048636,000355: # 0 048637,000356: 048638,000357: 06,3753 BANK 06 048639,000358: 06,2000 SETLOC EARTHLOC 048640,000359: 06,2000 BANK 048641,000360: 06,3753 COUNT* $$/LUROT 048642,000361: 048643,000362: 06,3753 57545 EARTHL DLOAD DCOMP 048644,000363: 06,3754 01716 AXO 048645,000364: 06,3755 14017 STODL 504LPL 048646,000365: 06,3756 01714 -AYO 048647,000366: 06,3757 14021 STODL 504LPL +2 048648,000367: 06,3760 24007 LO6ZEROS 048649,000368: 06,3761 24023 STOVL 504LPL +4 048650,000369: 06,3762 00017 504LPL 048651,000370: 06,3763 77616 RVQ 048652,000371: 048653,000372: # Page 1148 048654,000373: # CONSTANTS AND ERASABLE ASSIGNMENTS 048655,000374: 048656,000375: 06,3764 12,2004 1B1 = DP1/2 # 1 SCALED B-1 048657,000376: 06,3764 0000050 RPREXIT = S1 # R-TO-RP AND RP-TO-R SUBR EXIT 048658,000377: 06,3764 0000051 EARTHMXX = S2 # EARTHMX, MOONMX SUBR. EXITS 048659,000378: 06,3764 504RPR = 0D # 6 REGS R OR RP VECTOR 048660,000379: 06,3764 SINNODI = 8D # 2 SIN(NODI) 048661,000380: 06,3764 DVECTR = 8D # 6 D VECTOR MOON 048662,000381: 06,3764 CVECTR = 8D # 6 C VECTR MOON 048663,000382: 06,3764 504AZ = 18D # 2 AZ 048664,000383: 06,3764 TIMSUBM = 14D # 3 TIME SUB M (MOON) T+T0 IN GETAZ 048665,000384: 06,3764 504LPL = 14D # 6 L OR LP VECTOR 048666,000385: 06,3764 AVECTR = 20D # 6 A VECTOR (MOON) 048667,000386: 06,3764 BVECTR = 26D # 6 B VECTOR (MOON) 048668,000387: 06,3764 MMATRIX = 20D # 18 M MATRIX 048669,000388: 06,3764 COB = 32D # 2 COS(B) B-1 048670,000389: 06,3764 SOB = 34D # 2 SIN(B) B-1 048671,000390: 06,3764 504F = 6D # 2 F(MOON) 048672,000391: End of include-file PLANETARY_INERTIAL_ORIENTATION.agc. Parent file is MAIN.agc