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I will try to explain what the Fourier expansion of a "modularÌýform" on an exceptional group looks like, from the point of view of theÌýarchimedean place.Ìý In more detail, Gross-Wallach and Gan-Gross-Savin haveÌýsingled out what a modular form on an exceptional group G should be: TheÌýreal points G(R) should make up the so-called quaternionic real form of G,Ìýand then modular forms F on G correspond to automorphic forms whoseÌýinfinite component belongs to the quaternionic discrete series.Ìý In such aÌýsituation, the Fourier expansion of F is controlled by what is calledÌýgeneralized Whittaker function.Ìý Wallach has studied these functions, andÌýproved (abstractly) that they satisfy a finite multiplicity statement.ÌýWhen this finite multiplicity is 1, it makes sense to ask for a formula forÌýthe generalized Whittaker function.Ìý I will give a formula in the aboveÌý²õ±ð³Ù³Ù¾±²Ô²µ.