Merged help allows authors to separate their content into different files and have the content merged at runtime by the HH viewer into one cohesive unit, allowing several CHM files to act as one CHM. There are two mechanisms used with CHMs to achieve this; collections and CHM-based.
This involves an XML file with an extension of .col that contains information on the files to be merged at runtime. The advantage of this is that since the collection file is XML it can be easily modified to accomodate new pieces of documentation.
With this mechanism instructions in a CHM indicate that it should be merged with other CHMs. The advantage of this system is that modification is currently difficult. The inability to modify CHMs is useful where there is no need to change which files are merged very often.
