string sSEP = "|";

list lsystem(string smessage)
{ //Converts message (converted with llDumpList2String() with sSEP as separator from a valid particlesystem-list) back to a particlesystem-list again.
  list lnew;
  list lj = llParseString2List(smessage, [sSEP], []);
  integer iC; integer iE; integer iV; integer iT;
  for (iC = 0; iC < llGetListLength(lj); iC = iC + 2)
  {
    iE = (integer)llList2String(lj, iC);
    iV = llListFindList(lpsystem, [iE]);
    iT = llList2Integer(ltypes, iV);
    if (iT == 1)
    {
     lnew += [iE] + llList2Integer(lj, iC+1);
    }
    else if (iT == 2)
    {
     lnew += [iE] + llList2Float(lj, iC+1);
    }
    if (iT == 3)
    {
     lnew += [iE] + (vector)llList2String(lj, iC+1);
    }
    if (iT == 4)
    {
     lnew += [iE] + (key)llList2String(lj, iC+1);
    }
    if (iT == 5)
    {
     lnew += [iE] + llList2String(lj, iC+1);
    }
  }
  return lnew;
}

list lpsystem =
[PSYS_PART_FLAGS,
PSYS_SRC_PATTERN ,
PSYS_SRC_BURST_RADIUS,
PSYS_SRC_ANGLE_BEGIN,
PSYS_SRC_ANGLE_END,
PSYS_SRC_TARGET_KEY,
PSYS_PART_START_COLOR,
PSYS_PART_END_COLOR,
PSYS_PART_START_ALPHA,
PSYS_PART_END_ALPHA,
PSYS_PART_START_SCALE,
PSYS_PART_END_SCALE,
PSYS_SRC_TEXTURE,
PSYS_PART_START_GLOW,
PSYS_PART_END_GLOW,
PSYS_PART_BLEND_FUNC_SOURCE,
PSYS_PART_BLEND_FUNC_DEST,
PSYS_SRC_MAX_AGE,
PSYS_PART_MAX_AGE,
PSYS_SRC_BURST_RATE,
PSYS_SRC_BURST_PART_COUNT,
PSYS_SRC_ACCEL,
PSYS_SRC_OMEGA,
PSYS_SRC_BURST_SPEED_MIN,
PSYS_SRC_BURST_SPEED_MAX];
/*1 = integer
2 = float
3 = vektor
4 = key
5 = string */
list ltypes =
[1,
1,
2,
2,
2,
4,
3,
3,
2,
2,
3,
3,
5,
2,
2,
1,
1,
2,
2,
2,
1,
3,
3,
2,
2];

default
{
    state_entry()
    { //Test.
        list ltestsystem = [
        PSYS_PART_FLAGS,       PSYS_PART_WIND_MASK | PSYS_PART_EMISSIVE_MASK,
        PSYS_SRC_PATTERN,      PSYS_SRC_PATTERN_EXPLODE,
        PSYS_PART_START_COLOR, <1.0, 0.0, 0.0>
        ];
        string stestsystem = llDumpList2String(ltestsystem, sSEP);
        list lconvertedback = lsystem(stestsystem);
        llOwnerSay(llDumpList2String(ltestsystem, "_"));
        llOwnerSay(llDumpList2String(lconvertedback, "_"));
        //Output:
        //[14:14] Object: 0_264_9_2_1_<1.000000, 0.000000, 0.000000>
        //[14:14] Object: 0_264_9_2_1_<1.000000, 0.000000, 0.000000>
    }
}