diff --git a/Pwsh/Obsession/CustomEnumFormatInfo.ps1 b/Pwsh/Obsession/CustomEnumFormatInfo.ps1
new file mode 100644
index 0000000..79a3a9a
--- /dev/null
+++ b/Pwsh/Obsession/CustomEnumFormatInfo.ps1
@@ -0,0 +1,98 @@
+<#
+this script outputs:
+Name                                     Value
+----                                     -----
+4294967296 | Join-String -f '{0:x}'      100000000
+'{0:x}' -f $o                            0000000100000000
+'{0:x}' -f $o.value__                    100000000
+$o.ToString('x')                         0000000100000000
+$o.value__.ToString('x')                 100000000
+Join-String -f '{0:x}'                   0000000100000000
+Join-String -f '{0:x}' -Property value__ 100000000
+[enum]::Format( [e], $o.value__, 'x' )   0000000100000000
+[enum]::Format( [e], $o, 'x' )           0000000100000000
+
+
+F1 F2    Str1 Str2             ToStr_None ToStr_F1         '{0:x}' -f enum  '{0:x}' -f enum.value__
+-- --    ---- ----             ---------- --------         ---------------  -----------------------
+G  {0:G} G    A                A          A                0000000100000000 100000000
+g  {0:g} g    A                A          A                0000000100000000 100000000
+F  {0:F} F    A                A          A                0000000100000000 100000000
+f  {0:f} f    A                A          A                0000000100000000 100000000
+D  {0:D} D    4294967296       A          4294967296       0000000100000000 100000000
+d  {0:d} d    4294967296       A          4294967296       0000000100000000 100000000
+X  {0:X} X    0000000100000000 A          0000000100000000 0000000100000000 100000000
+x  {0:x} x    0000000100000000 A          0000000100000000 0000000100000000 100000000
+#>
+
+@'
+See also:
+    - [docs: enum format strings](https://learn.microsoft.com/en-us/dotnet/standard/base-types/enumeration-format-strings)
+'@
+function tryAll {
+
+    param(
+        [enum]$Obj
+    )
+    'G','g', 'F','f', 'D', 'd', 'X', 'x' | %{
+        $fStr = $_
+        $PosStr = '{0:', $fstr, '}' -join ''
+        [pscustomobject]@{
+            F1     = $Fstr
+            F2     = $PosStr
+
+            Str1 = $Fstr -f $Obj
+            Str2 = $PosStr -f $Obj
+
+            ToStr_None    = $Obj.ToString()
+            ToStr_F1 = $Obj.ToString( $fstr )
+
+            "'{0:x}' -f enum"  = '{0:x}' -f $Obj
+            "'{0:x}' -f enum.value__"  = '{0:x}' -f $Obj.value__
+        }
+    }
+}
+[Flags()]
+enum e : ulong
+{
+  A  = 0x100000000
+  B  = 0x200000000
+}
+
+'0x{0:X}' -f ([e]'A, B').value__
+'{0:x}' -f ([e]'A, B').value__
+[e]'A, B' | Join-String -f '{0:x}' { $_ }
+$o = [e]'A'
+
+[ordered]@{
+    "4294967296 | Join-String -f '{0:x}'" =
+        4294967296 | Join-String -f '{0:x}'
+
+    "'{0:x}' -f `$o" =
+        '{0:x}' -f $o
+
+    "'{0:x}' -f `$o.value__" =
+        '{0:x}' -f $o.value__
+
+    "`$o.ToString('x')" =
+        $o.ToString('x')
+
+    "`$o.value__.ToString('x')" =
+        $o.value__.ToString('x')
+
+    "Join-String -f '{0:x}'" =
+        $o | Join-String -f '{0:x}'
+
+    "Join-String -f '{0:x}' -Property value__" =
+        $o | Join-String -f '{0:x}' -Property value__
+
+    "[enum]::Format( [e], `$o.value__, 'x' )" =
+        [enum]::Format( [e], $o.value__, 'x' )
+
+    "[enum]::Format( [e], `$o, 'x' )" =
+        [enum]::Format( [e], $o, 'x' )
+
+} |
+ft -AutoSize
+
+tryAll $o|ft