You can specify alternation of steps in XBetza using parenteses plus a number for specifying the repeating combination. Becaust F and D are incommensurate, you will first have to express D in K steps: D = mpafW to transparently glue to W steps together. The repeating unit then is mpafafsW, and te trajectory that starts with a D step and ends with an F step is mpafafs(aqmpafafq)2W
You can specify alternation of steps in XBetza using parenteses plus a number for specifying the repeating combination. Becaust F and D are incommensurate, you will first have to express D in K steps: D = mpafW to transparently glue to W steps together. The repeating unit then is mpafafsW, and te trajectory that starts with a D step and ends with an F step is mpafafs(aqmpafafq)2W