According to an announcement on the ScotlandsPeople web site at: http://bit.ly/2seqPml:
“From 26 June 2017, more than 36,000 new presbyterian church records, covering the period 1744 to 1855 have been added to ScotlandsPeople’. The 20,255 births and baptisms (1744-1855), 10,368 marriages and proclamations (1729-1855) and 5,422 death and burial records (1783-1855) may be especially helpful for anyone searching for a person born or baptised, married or died before the introduction of statutory registration in 1855. Further information about our church registers can be found in our record guide.
“Old Parish Registers (OPRs), already available to search through the website, were compiled by ministers of the Church of Scotland, and therefore do not include surviving records of baptisms that were created in other presbyterian denominations that separated themselves from the established church and sometimes also formed further separate denominations.”
You can read the full announcement at: http://bit.ly/2seqPml.