Appellism is an ideology come up from The Invisible Committee from their text called "The Call" (
https://theanarchistlibrary.org/library/anonymous-call). They are a part of the anarchist side of communization and, like mainstream communization, they support the immediacy of revolution and the abolition of the working class. They are also insurrectionist.
From what I've heard they are very problematic, with some individuals claiming that they harass fellow anarchists who disgaree with them. There's this article written by an ex-member of the appelistes, claiming that they were bigotted, didn't protect the women within the appelist circle from rapists, and that they were hostile towards other anarchists. (
https://anarchistnews.org/content/jumping-ship-or-why-im-defecting-terrible-community)
They have also been seen as reformist, as one anarchist claims that they were "the French tiqqunists who sold out anarchists at the Zad in order to negotiate for state-sanctioned land projects." (
https://theanarchistlibrary.org/library/some-intractables-more-talk-more-rock).
Both the articles linked give a lot more detail to how problematic they are, so please read them if you want more detail.