Standing for the Ten Commandments

There is a question among the Poskim as to whether the custom to stand up during the Aliyah of the Ten Commandments (Aseret Hadibrot) on Shavuot is appropriate or not. This custom, prominent among Moroccans, Ashkenazim and others, dates back to at least the time of the Rambam, who disagreed with it.  The basis of the Rambam’s resistance to this Minhag was that it may appear to the congregants that only the Ten Commandments are important while the remainder of the Torah is superfluous.
The HIDA (LeDavid Emet 7:5 and in Tov Ayin 11) does not share the Rambam’s concern because on Shavuot there are other portions of the Torah that are read in addition to the Ten Commandments, which proves that all of the Torah is important. Furthermore, the Rama rules (Orah Haim 1:5) that if it is the only portion being read, the Ten Commandments should not be read in public, out of concern that heretics will claim that only that portion is true. Rabbi Shalom Messas (Shemesh Umagen O.H. 1: 57), Rabbi Yehudah Ayash (Mateh Yehudah 1:6) and Rabbi Moshe Feinstein (Igrot Moshe, O.H. 4:22) all allay the concern regarding heretics because, nowadays a heretic is unlikely to believe only part of the Torah is true, but rather deny the entire Torah, Ten Commandments included.
Although there are some that follow the approach of the Rambam, such as Rav Ovadia Yosef, standing up during Aseret Hadibrot is a longstanding tradition and is the custom among Moroccans.   However it is noteworthy to mention that the HIDA writes that is considered disrespectful for a portion of congregants to sit during Aseret Hadibrot in a community whose Minhag is to stand. Rav Ovadia Yosef (Yehave Daat 6:8) says that such people should at least stand at the beginning of the Aliyah so that the community acts uniformly.
Summary: The Moroccan custom is to stand up during the Aliyah of Aseret Hadibrot on Shavuot. It is improper to sit down in a community that stands up.