Dateinamen in Serie erweitern

@echo off & setlocal ENABLEDELAYEDEXPANSION
set "Pfad=C:\Pfadzudendateien\*.MPF"  
for /f "delims=" %%a in ('dir /B /S /A-D "%Pfad%"') DO @(  
 set filename=%%~nxa
 set newname=PR_!filename:~1!
 ren "%%~a" "!newname!"  
)

dir "C:\Pfadzudendateien\*.MPF" | ?{!$_.PSIscontainer} | %{rename-item $_.Fullname "$($_.Name.Substring(0,1))R_$($_.Name.Substring(1))"}  

for /f "delims" %%a in ('dir /B /S /A-D "%Pfad%"') do for /f "tokens=1* delims=P" %%i in ("%%~nxa") do ren "%%a" "PR_%%i%%j"

for /f "delims" %%a in ('dir /B /S /A-D "%Pfad%"') do (  
    for /f "tokens=1* delims=P" %%i in ("%%~nxa") do ren "%%a" "PR_%%i%%j"  
)

set "Pfad=C:\Pfadzudendateien\P*.MPF"