Writing in the context of libburnia means the transfer of a byte stream onto optical media or into disk filesystem objects which are handled much like optical media.
The various types of optical media show quite different capabilities and behavior. CD media can carry raw audio streams as well as data blocks which are protected by checksums and error correction. DVD and BD media can only carry data blocks. Eventual audio or video information is encoded in these blocks and not in raw streams.
There is the class of multi-session media: CD-R, CD-RW, DVD-R, DVD-RW, DVD+R, BD-R, which have a table of content describing their session history. They may only be written sequentially and in large sessions.
The other class is the one of overwriteable media: formatted DVD-RW, DVD+RW, DVD-RAM, BD-RE, which offers no session history but allows to perform random access writing with a certain granularity.
libburnia performs its writing via libburn which demands a certain respect towards the peculiarities of the media type. Under the special assumption that only ISO 9660 filesystems with Rock Ridge extensions get written, libisoburn offers writing capabilities which are nearly independent of the media type.
Formatted CD-RW are not yet supported by libburn.
Regular disk files and block devices may be used like overwriteable media. Other disk filesystem objects may be used as empty multi-session media.