diff --git a/magic/Magdir/ibm370 b/magic/Magdir/ibm370
index dc976f87..c3153b84 100644
--- a/magic/Magdir/ibm370
+++ b/magic/Magdir/ibm370
@@ -4,7 +4,7 @@
 # ibm370:  file(1) magic for IBM 370 and compatibles.
 #
 # "ibm370" said that 0x15d == 0535 was "ibm 370 pure executable".
-# What the heck *is* "USS/370"?
+# "USS/370" is an old name for the z/OS Unix subsystem
 # AIX 4.1's "/etc/magic" has
 #
 #	0	short		0535		370 sysV executable
@@ -50,3 +50,9 @@
 # NETDATA (https://en.wikipedia.org/wiki/NETDATA)
 #	-\INMR01 In EBCDIC
 0	string 		\x60\xe0\xc9\xd5\xd4\xd9\xf0\xf1	IBM NETDATA file
+
+# z/OS Program Object executable
+# Starts with "IEWPLMH" in EBCDIC, followed by a single EBCDIC space to pad
+# to 8 bytes. According to https://www.ibm.com/support/pages/apar/PK91585
+# IEWPLMH is eyecatcher for "Binder Program Load Module Header" control block
+0	string   	\xc9\xc5\xe6\xd7\xd3\xd4\xc8\x40	z/OS Program Object executable