diff --git a/tools/test-nm-biu-to-ascii-mm-round-tripping.cpp b/tools/test-nm-biu-to-ascii-mm-round-tripping.cpp
new file mode 100644
index 0000000000..d44b7dc785
--- /dev/null
+++ b/tools/test-nm-biu-to-ascii-mm-round-tripping.cpp
@@ -0,0 +1,121 @@
+
+/*
+    A test program to which explores the ability to round trip a nanometer
+    internal unit in the form of a 32 bit int, out to ASCII floating point
+    millimeters and back in without variation.  It tests all 4 billion values
+    that an int can hold, and converts to ASCII and back and verifies integrity
+    of the round tripped value.
+
+    Author: Dick Hollenbeck
+*/
+
+
+#include <limits.h>
+#include <stdio.h>
+#include <math.h>
+#include <string>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+
+static inline int KiROUND( double v )
+{
+    return int( v < 0 ? v - 0.5 : v + 0.5 );
+}
+
+
+typedef int             BIU;
+
+#define BIU_PER_MM      1e6L
+
+
+//double  scale = BIU_PER_MM;
+//double  scale = UM_PER_BIU;
+long double scale = 1.0L/BIU_PER_MM;
+
+
+std::string biuFmt( BIU aValue )
+{
+    long double engUnits = aValue * scale;
+    char        temp[48];
+    int         len;
+
+    if( engUnits != 0.0 && fabsl( engUnits ) <= 0.0001 )
+    {
+        snprintf( temp, sizeof(temp), "%.10Lf", engUnits );
+
+        len = strlen( temp );
+
+        while( --len > 0 && temp[len] == '0' )
+            temp[len] = '\0';
+
+        ++len;
+    }
+    else
+    {
+        len = snprintf( temp, sizeof(temp), "%.10Lg", engUnits );
+    }
+
+    return std::string( temp, len );;
+}
+
+
+int parseBIU( const char* s )
+{
+    long double d = strtold( s, NULL );
+    return KiROUND( double( d * BIU_PER_MM ) );
+}
+
+
+int main( int argc, char** argv )
+{
+    unsigned mismatches = 0;
+
+    if( argc > 1 )
+    {
+        // take a value on the command line and round trip it back to ASCII.
+
+        int i = parseBIU( argv[1] );
+
+        printf( "%s: i:%d\n", __func__, i );
+
+        std::string s = biuFmt( i );
+
+        printf( "%s: s:%s\n", __func__, s.c_str() );
+
+        exit(1);
+    }
+
+    // printf( "sizeof(long double): %zd\n", sizeof( long double ) );
+
+    // Emperically prove that we can round trip all 4 billion 32 bit integers representative
+    // of nanometers out to textual floating point millimeters, and back without error using
+    // the above two functions.
+//    for( int i = INT_MIN;  int64_t( i ) <= int64_t( INT_MAX );  ++i )
+    for( int64_t j = INT_MIN;  j  <= int64_t( INT_MAX );  ++j )
+    {
+        int i = int( j );
+
+        std::string s = biuFmt( int( i ) );
+
+        int r = parseBIU( s.c_str() );
+
+        if( r != i )
+        {
+            printf( "i:%d  biuFmt:%s  r:%d\n", i, s.c_str(), r );
+            ++mismatches;
+        }
+
+        if( !( i & 0xFFFFFF ) )
+        {
+            printf( " %08x", i );
+            fflush( stdout );
+        }
+    }
+
+    printf( "mismatches:%u\n", mismatches );
+
+    return 0;
+}
+