What better place to get some first hand information on the Scottish way of doing things - nothing like getting it straight from the horses mouth, so to speak. ;-)).

In English/Welsh heraldry, the usual mark of bastardy since the late 18th century has been the bordure wavy, but the bendlet sinister was once frequently used. Bordures plain, compony and engrailled are also occasionally found. The baton sinister (usually of a metal) has been used almost exclusively for royal bastards. The arms of William IV's nine bastard, the Fitz Clarences, were differenced by a variety of batons sinister.

However, with reference to the bordure compony in Scotland, do not take it as having the same connotation in other heraldic jurisdictions. The method of indicating illegitimacy [if indicated at all] differed/differs from heraldic jurisdiction to jurisdiction and what may apply in one may have a completely different connotation elsewhere. So it is imperative that you seek out the specific information that applies to the subject heraldic jurisdiction.

You would have to either get to a public library for some reference books or purchase some for yourself and some of them can be quite expensive. For anyone interested in learning about the British system(s) of Heraldry I can only suggest thet you try and peruse a copy of the following books:
'Boutell's Heraldry', 'The Oxford Guide to Heraldry' and/or Fox-Davies' 'A Complete Guide to Heraldry'.