If the description includes some type of reference to physical media, there's a pretty good chance that the material is outdated.
When CDs first came out, it was touted that you could store 150 Bibles or 4.5 million characters on a single CD-ROM.
Now, these types of measurements are antiquated since we have a different perception of storage space as it relates to media. For example, we know a CD can now hold around 100 mp3's or a single feature film.
But even then, we no longer think in terms of optical storage at all, since a 4GB flash drive goes for less than $10.