The Web and WOFF versions are designed for embedding on web sites. To keep them small, they lack most of the symbols found in the Print/PDF version and have no Petite Capitals, but they do include  Small Capitals, and the *.otf versions are hinted. 

They contain some OpenType features, such as Small Capitals, Capitals to Small Capitals, Standard Ligatures, Discretionary Ligatures, Superscripts, Subscripts, Scientific Inferiors, Ordinals, OldStyle Figures,  Fractions, and Kerning.

They have the same font name (Verajja) as the Print/PDF versions, so it is not possible to install them simultaneously. (However, the *.otf filenames are different to avoid overwriting the other versions in error).  So make sure that you have the appropriate version installed for Print or Web publishing. 

The WOFF (Web Open Font Format) versions are the same as the OpenType Web versions, but compressed. The disadvantage is that they cannot be installed in Windows and cannot be embedded automatically using Serif WebPlus X8.  You will need to add suitable @FontFace code manually to make use of them.

The WOFF2 versions are smaller due to better compression. Most browsers now support them. 

Google Chrome (since version 36)
Edge (since version 14)
Opera (since version 26)
Firefox (since version 35)
Safari (since version 10)
