PROTOCOL.md: fixed typo.

doc/PROTOCOL.md

@@ -365,8 +365,8 @@ A download might be:
 'api/download.php' will be called with a SIP (no other vars used). The SIP contains:
   * DOWNLOAD_EXPORT_FILENAME - any target filename, if none given take DOWNLOAD_OUTPUT_PDF ('output.pdf'). 
   * DONWLOAD_MODE - file / pdf / excel / zip. If not specified:
-      a) 'file' is the default if only one is given and if this is a file.
-      b) 'pdf' is the default if there are multiple TOKEN_URL, TOKEN_URL_PARAM, TOKEN_FILE in SIP_DOWNLOAD_PARAMETER found.
+      a) 'file' is the default, if only one source is given and if that is a file.
+      b) 'pdf' is the default, if there are multiple TOKEN_URL, TOKEN_URL_PARAM, TOKEN_FILE in SIP_DOWNLOAD_PARAMETER found.
   * SIP_DOWNLOAD_PARAMETER (base64 encoded) - contains all parameter to source elements. 
     Format: <format 1>:<element 1>|<format 2>:<element 2>|...|<format n>:<element n>|