What about the FHS?

Clearly, in the ideal world all distros would be 100% FHS compliant. Many already are, but this unfortunately does not get us very far, as the FHS is at times a rather vague document, with plenty of room for interpretation. For instance, some distros put KDE into /usr , some into /usr/local , and some into /opt. All of these are potentially correct interpretations of the standard. Working on improving the FHS is one of the priorities of this project, as often conflicting prefixes is the only problem faced in making a package cross-distro, but often there are other reasons for needing to choose the prefix as well. Sometimes it's personal preference: some people abhor putting stuff into /opt, some put everything there. Some do both. By default, the install prefix will always be as FHS compliant as possible in any autopackage, unless the prefix needs to deviate from the spec in order for the package to work properly.