Just have a minute on the road.
So, is the 3rd party airport 'sloped' ?
Remembering that the ARP is the center of the RWY axis, what do you want the ARP Altitude to be if that 3rd party airport is modded to be 'sloped' ?
GaryGB
Yes it has , here its the sloped codes in AP's XML :
<Runway lat="35.6900572031736" lon="51.3147675991058" alt="1181.865" heading="109.650" length="3644.000" width="45.000" patternAltitude="304.800" surface="{2E0DE83F-B79A-4435-905C-DCBBEAC55C59}" transparent="TRUE" number="11" designator="LEFT" primaryTakeoff="TRUE" primaryPattern="LEFT" secondaryTakeoff="TRUE" secondaryPattern="LEFT" primaryMarkingBias="0.0000" secondaryMarkingBias="0.0000" groundMerging="FALSE" excludeVegetationAround="TRUE">
<RunwayDeformation alt="1204.400" ratio="0.0000" />
<RunwayDeformation alt="1198.700" ratio="0.2042" />
<RunwayDeformation alt="1185.000" ratio="0.4997" />
<RunwayDeformation alt="1178.000" ratio="0.6035" />
<RunwayDeformation alt="1158.500" ratio="1.0000" />
<Markings edges="FALSE" threshold="FALSE" alternateThreshold="FALSE" fixedDistance="FALSE" alternateFixedDistance="FALSE" touchdown="FALSE" alternateTouchdown="FALSE" dashes="TRUE" ident="FALSE" leadingZeroIdent="FALSE" precision="FALSE" alternatePrecision="FALSE" edgePavement="FALSE" singleEnd="FALSE" primaryClosed="FALSE" secondaryClosed="FALSE" primaryStol="FALSE" secondaryStol="FALSE" noThresholdEndArrows="FALSE" />
<Lights center="NONE" centerRed="FALSE" edge="HIGH" />
<OffsetThreshold end="PRIMARY" length="850.000" width="45.000" surface="{00000000-0000-0000-0000-000000000000}" />
<ApproachLights end="PRIMARY" system="NONE" reil="FALSE" endLights="TRUE" touchdown="FALSE" snapToGround="FALSE" spacing="30.400" offset="30.480" slope="0.000" />
<ApproachLights end="SECONDARY" system="CALVERT" reil="FALSE" strobes="215" endLights="TRUE" touchdown="FALSE" snapToGround="FALSE" spacing="27.500" offset="30.480" slope="359.600" />
<Vasi end="SECONDARY" type="PAPI4" side="LEFT" spacing="90.000" pitch="3.100" biasX="35.369" biasZ="1403.244" />
<RunwayStart end="PRIMARY" lat="35.6929117441177" lon="51.3048514723778" alt="1181.605" heading="109.670" />
<RunwayStart end="SECONDARY" lat="35.6846287474036" lon="51.3336324691772" alt="1181.482" heading="289.670" />
</Runway>
<Runway lat="35.6885511428118" lon="51.3126562535763" alt="1181.860" heading="109.680" length="4041.000" width="60.000" patternAltitude="304.800" surface="{2E0DE83F-B79A-4435-905C-DCBBEAC55C59}" transparent="TRUE" number="11" designator="RIGHT" primaryLanding="TRUE" primaryTakeoff="TRUE" primaryPattern="LEFT" secondaryLanding="TRUE" secondaryPattern="LEFT" primaryMarkingBias="0.0000" secondaryMarkingBias="0.0000" groundMerging="FALSE" excludeVegetationAround="TRUE">
<RunwayDeformation alt="1204.000" ratio="0.0000" />
<RunwayDeformation alt="1195.700" ratio="0.1423" />
<RunwayDeformation alt="1187.600" ratio="0.3690" />
<RunwayDeformation alt="1173.300" ratio="0.6248" />
<RunwayDeformation alt="1156.000" ratio="1.0000" />
<Markings edges="FALSE" threshold="FALSE" alternateThreshold="FALSE" fixedDistance="FALSE" alternateFixedDistance="FALSE" touchdown="FALSE" alternateTouchdown="FALSE" dashes="TRUE" ident="FALSE" leadingZeroIdent="FALSE" precision="FALSE" alternatePrecision="FALSE" edgePavement="FALSE" singleEnd="FALSE" primaryClosed="FALSE" secondaryClosed="FALSE" primaryStol="FALSE" secondaryStol="FALSE" noThresholdEndArrows="FALSE" />
<Lights center="NONE" centerRed="FALSE" edge="HIGH" />
<ApproachLights end="PRIMARY" system="SSALS" reil="FALSE" endLights="TRUE" touchdown="FALSE" snapToGround="FALSE" spacing="30.400" offset="30.480" slope="0.800" />
<ApproachLights end="SECONDARY" system="CALVERT" reil="FALSE" endLights="TRUE" touchdown="FALSE" snapToGround="FALSE" spacing="30.400" offset="30.480" slope="359.800" />
<Vasi end="PRIMARY" type="PAPI4" side="LEFT" spacing="90.000" pitch="3.400" biasX="46.474" biasZ="1617.877" />
<Vasi end="SECONDARY" type="PAPI4" side="LEFT" spacing="90.000" pitch="3.300" biasX="45.276" biasZ="1707.838" />
<RunwayStart end="PRIMARY" lat="35.694535151124" lon="51.2921065092087" alt="1181.480" heading="109.766" />
<RunwayStart end="SECONDARY" lat="35.6825724989176" lon="51.3331045210361" alt="1181.479" heading="289.766" />
</Runway>