UPMIFA and an endowment

I am president of a foundation that serves churches. A donor established an endowment 15 year ago in his will for the purpose of providing a scholarship through a particular local church. The will has the following verbiage instructing the endowment. "Each year 90% of the income is to be distributed to the church and 10% is to be held as a hedge against inflation." There has been some discussion that according to UPMIFA (Georgia) the income can be not only the dividends/interest but also the appreciation of the base amount of the endowment. The thought then is that 4% of the principal of the endowment could be distributed subject to the 90% rule. Please give me your thoughts.