Spaces should never ever be used ... Though they don't make a difference technically , underscores make it more readable. Assigning one fixed length module-name as a prefix (Fin_<tablename/viewname>)  makes a good practice, the benefits of which can't be anticipated sometimes. Its a lot of relief when one has a need to develop an application for audits /security / licensing purposes especially where you can easily identify objects which follow one naming convention.