I suggest reviewing Section 2.2. of Reading 45 in regard to major components of an IPS. While a PM could certainly exclude securities below a certain credit rating (investment constraints) and specify an acceptable level of margin (investment constraints), there is no way that he could guaranty a particular rate of return, given a level of risk.
Note that this is different than specifying the level of risk that may be taken within the portfolio, which would certainly be part of an IPS.