Below is included the documentation for this field type from the ISO standard.
5.11 SFVec2f and MFVec2f
The SFVec2f field or event specifies a two-dimensional (2D)
vector. An MFVec2f field or event specifies zero or more 2D
vectors. SFVec2f's and MFVec2f's are written to the VRML file as
a pair of ISO C floating point values (see 2.[ISOC]) separated by
whitespace. For example:
fooVec2f [ 42 666, 7 94 ]
is an MFVec2f field, fooVec2f, with two valid vectors.
The initial value of an SFVec2f eventOut is (0 0). The initial value
of an MFVec2f eventOut is [ ].