Pre 1855 BMDs are on old parish records (OPRs) you can view them at
Scotland's People but mostly they do not contain any more information than
the IGI (FamilySearch) that you can search for free
The IGI lists
- the child's names
- the parents' names (including mother's maiden surname)
- date and parish of baptism
- sometimes date of birth
assuming of course that the information is in the original record. (I have seen records that say no more than 'xxx had a child baptised').
The OPR records generally contain one or more of the following
- parents' place of residence
- father's occupation
- whether the child was or was not legitimate
- whether the child was posthumous
- where the baptism took place
- names, residences and occupations of witnesses to the baptism
- relationship of the witnesses to the child, if any
- the name of the person after whom the child was named
- the relationship to the child of the person after whom (s)he was named, if any
- how many children the parents had
- name of the officiating minister
- denomination of the church into which the child was baptised
The vast majority of the OPR baptism records that I have seen* contain at least one of these extra pieces of information, but none contain all of them.
For example I have only ever seen the name and relationship of the person after whom the child was named in the Dundee parish register.
*For my own tree I have seen and transcribed, so far, 4346 such records. I have probably viewed at least as many again who have turned out not to be related to me. 8000-odd is only a fraction of the available records, of course, but it's probably a fairly representative sample.
The IGI is not comprehensive. It covers the northern part of Scotland pretty well, but there are many gaps in its coverage of the southern counties, for which the only source is the OPR index on Scotland's People. The IGI is unrivalled for finding births between 1855 and 1874, and (or so I am led to believe) some in 1881 and 1891, and useful for picking up creative spellings of names in the areas it does cover well.
Scotland's People has a very nearly complete index to the OPRs, and the index, which is also free to search, includes all the same information as the IGI except that if both birth and baptism date are in the original, SP only indexes the baptism date. (Oddly, it indexes both dates in the RC and Other Churches registers.)
So please don't rely on the IGI containing all the information available. It's a very useful tool, but it doesn't contain anything like the same amount of information as the OPRs.