A few constants where they belong

Marlin/Marlin_main.cpp

     //this is dangerous if a mixing of serial and this happens
     strcpy(&(cmdbuffer[bufindw][0]),cmd);
     SERIAL_ECHO_START;
-    SERIAL_ECHOPGM("enqueing \"");
+    SERIAL_ECHOPGM(MSG_Enqueing);
     SERIAL_ECHO(cmdbuffer[bufindw]);
     SERIAL_ECHOLNPGM("\"");
     bufindw= (bufindw + 1)%BUFSIZE;
     //this is dangerous if a mixing of serial and this happens
     strcpy_P(&(cmdbuffer[bufindw][0]),cmd);
     SERIAL_ECHO_START;
-    SERIAL_ECHOPGM("enqueing \"");
+    SERIAL_ECHOPGM(MSG_Enqueing);
     SERIAL_ECHO(cmdbuffer[bufindw]);
     SERIAL_ECHOLNPGM("\"");
     bufindw= (bufindw + 1)%BUFSIZE;

Marlin/SdFatConfig.h

  */
 /** Number of VFAT entries used. Every entry has 13 UTF-16 characters */
 #define MAX_VFAT_ENTRIES (2)
+/** Number of UTF-16 characters per entry */
+#define FILENAME_LENGTH 13
 /** Total size of the buffer used to store the long filenames */
-#define LONG_FILENAME_LENGTH (13*MAX_VFAT_ENTRIES+1)
+#define LONG_FILENAME_LENGTH (FILENAME_LENGTH*MAX_VFAT_ENTRIES+1)
 #endif  // SdFatConfig_h
 
 

Marlin/cardreader.cpp

     if( DIR_IS_SUBDIR(&p) && lsAction!=LS_Count && lsAction!=LS_GetFilename) // hence LS_SerialPrint
     {
 
-      char path[13*2];
-      char lfilename[13];
+      char path[FILENAME_LENGTH*2];
+      char lfilename[FILENAME_LENGTH];
       createFilename(lfilename,p);
       
       path[0]=0;
     while(*t!=0 && cnt< MAXPATHNAMELENGTH) 
     {t++;cnt++;}  //crawl counter forward.
   }
-  if(cnt<MAXPATHNAMELENGTH-13)
+  if(cnt<MAXPATHNAMELENGTH-FILENAME_LENGTH)
     file.getFilename(t);
   else
     t[0]=0;
       //SERIAL_ECHO("end  :");SERIAL_ECHOLN((int)(dirname_end-name));
       if(dirname_end>0 && dirname_end>dirname_start)
       {
-        char subdirname[13];
+        char subdirname[FILENAME_LENGTH];
         strncpy(subdirname, dirname_start, dirname_end-dirname_start);
         subdirname[dirname_end-dirname_start]=0;
         SERIAL_ECHOLN(subdirname);
       //SERIAL_ECHO("end  :");SERIAL_ECHOLN((int)(dirname_end-name));
       if(dirname_end>0 && dirname_end>dirname_start)
       {
-        char subdirname[13];
+        char subdirname[FILENAME_LENGTH];
         strncpy(subdirname, dirname_start, dirname_end-dirname_start);
         subdirname[dirname_end-dirname_start]=0;
         SERIAL_ECHOLN(subdirname);

Marlin/cardreader.h

   bool logging;
   bool sdprinting ;  
   bool cardOK ;
-  char filename[13];
+  char filename[FILENAME_LENGTH];
   char longFilename[LONG_FILENAME_LENGTH];
   bool filenameIsDir;
   int lastnr; //last number of the autostart;
   SdVolume volume;
   SdFile file;
   #define SD_PROCEDURE_DEPTH 1
-  #define MAXPATHNAMELENGTH (13*MAX_DIR_DEPTH+MAX_DIR_DEPTH+1)
+  #define MAXPATHNAMELENGTH (FILENAME_LENGTH*MAX_DIR_DEPTH+MAX_DIR_DEPTH+1)
   uint8_t file_subcall_ctr;
   uint32_t filespos[SD_PROCEDURE_DEPTH];
   char filenames[SD_PROCEDURE_DEPTH][MAXPATHNAMELENGTH];