For reference, these are the types of promotion components available:

Part 'A':

Buy [X] of version [V] – e.g. buy 2 barbecue beans, small size

Buy [X] of items from category [C] – e.g. buy 5 items from 'books'

Buy [X] of product [P] – e.g. 1 barbecue beans (any size)

Spend [£][X]

Part 'B':

Get [X] of [V] for free – e.g. get 1 barbecue beans (small size) free

Get [X]% off [V] – e.g. get 10% off barbecue beans (small size)

Get [£][X] off – e.g. get £5 off

Get [X] of [P] for free – e.g. get 1 floor mat (any colour) free

Get [X]% off [P] – e.g. get 5% off 1 floor mat (any colour)

Get [X]% off items from category [C] – e.g. get 15% off any book

Key:

[X] = a whole number

[V] = a specific version of a product

[P] = a product (any version)

[C] = a category

[£] = the default currency (£, $, etc. depending on your store)