[R-SIG-Finance] Slots as @title and @documentation in S-Plus

[Wind]

In S-Plus, data frames have slots as @title and @documentation.  It seems that R is different.

After the following code:
vMatrix<-sqlQuery(sqlMatrix,sqlStr1) 
If I want to add some memo to vMatrix，it would be vMatrix at title="The first time and so on." in S-Plus.

But in R, data frame has no slots.
According to help and documentations, it seems that S4 class has slot. But data frame is not S4.   The S4/S3 confused me since I am new to R.

I wonder whether thers's easy way to attach some memo to a data frame, as in S-Plus.
Thanks.