Compatibility with previous EndNote versions
EndNote X9.3 and later versions are not compatible with EndNote libraries created in previous versions. When you open a library from an earlier version, you will get a dialog where you can confirm that it will be converted. You will also need to enter the name for the new library to be stored under. In other words, the result is a new, converted EndNote library in addition to keeping the old one unchanged.
Between versions X – X9.2:
EndNote X – X9 are compatible in between. So you can easily go from one version to another without converting the base. It should nevertheless be remembered that new functionality and new reference types are added in each version so that output styles etc. in an older version does not take these into account. It is therefore not advisable to go back and forth between versions versions that are too far apart in time. One up or down version should work just fine.
Between versions 5-9 and newer versions:
You can open libraries from earlier versions in the newer versions. These will then be converted to the new format. Always check for special characters etc. gets converted right.
Libraries from the latest versions cannot be opened in versions 5-9. The references must then be exported from the latest version and imported into the previous version via e.g. RIS format. You will not keep the ID numbering in the library. (This may cause references in Word documents not to be automatically recognized.)
Output styles, import filters, and connection files work regardless of version (with the reservation as described above).