In the next binary release** you will be able to use ranges and subranges in MxAlgebra expression. The range operator "x : y" creates a column vector of elements [x, x+1, x+2, ..., y]. In addition, the square bracket operator now supports subranges. The following are now valid MxAlgebra expressions:
foo foo foo foo foo foo foo
The square bracket operator is quite versatile. We have 25 test cases in our test suite devoted to this operator. If we missed a case, and you figure out some way to break the operator, please let us know.
** OpenMx 0.2.6. Version 0.2.5 has been released without a news announcement.