arglist = [myarg1, "displacement", "tmp.ps"]

# or with indices:
arglist[0] = myarg1; arglist[1] = 'displacement'; ...

# or with append:
arglist = []  # start with empty list
arglist.append(myarg1);
arglist.append("displacement");

[filename, plottitle, psfile] = arglist

# or with indices:
filename = arglist[0]; plottitle = arglist[1]; ...