diff -r 914c4a81027d -r ac10e32938df src/Pure/System/isabelle_platform.scala
--- a/src/Pure/System/isabelle_platform.scala	Tue Mar 26 17:06:23 2024 +0100
+++ b/src/Pure/System/isabelle_platform.scala	Tue Mar 26 17:27:35 2024 +0100
@@ -43,6 +43,11 @@
   val ISABELLE_WINDOWS_PLATFORM64: String = get("ISABELLE_WINDOWS_PLATFORM64")
   val ISABELLE_APPLE_PLATFORM64: String = get("ISABELLE_APPLE_PLATFORM64")
 
+  def ISABELLE_PLATFORM(windows: Boolean = false, apple: Boolean = false): String =
+    proper_string(if_proper(windows, ISABELLE_WINDOWS_PLATFORM64)) orElse
+    proper_string(if_proper(apple, ISABELLE_APPLE_PLATFORM64)) orElse
+    proper_string(ISABELLE_PLATFORM64) getOrElse error("Missing ISABELLE_PLATFORM64")
+
   def is_arm: Boolean =
     ISABELLE_PLATFORM64.startsWith("arm64-") ||
     ISABELLE_APPLE_PLATFORM64.startsWith("arm64-")