This create table command specifies a reservepagegap value of 16:
create table more_titles ( title_id tid, title varchar(80) not null, type char(12), pub_id char(4) null, price money null, advance money null, total_sales int null, notes varchar(200) null, pubdate datetime, contract bit ) lock datarows with reservepagegap = 16
Any operation that performs extent allocation on the more_titles table leaves 1 empty page for each 15 filled pages. For partitioned tables, the reservepagegap value applies to all partitions.
The default value for reservepagegap is 0, meaning that no space is reserved.