In ServiceDesk 7.x, in the process view, located in the Process History section of the page, there is an option to edit the process comments that are included as a part of any incident. As shown in the first screen shot below, selecting the icon at #1 allows you to begin the process. Selecting "Edit Comment", shown at #2 opens up the edit screen.
The screen shot below displays the resulting screen. Notice that you can change the comment title, and the view level. The "Public" view level is shown, but there are options for "Private", and "Admin". If you choose the "Admin" level, the Add User Level Comment checkbox is made available. This checkbox makes the comments that an admin creates available to all users. The other view level option is just that, private for the specific user modifying the comment.
In the "Comment:" section itself you can see that it has the original source text, and a reasonably featured HTML text editor, allowing formatting, graphics additions and other notes in the box. At the bottom, you can switch from Design view, to HTML, and then a preview of how the comment will appear. Save and Cancel are self-explanatory.
Some users and ServiceDesk administrators don't want users changing any comments entered in the incident (process)history, and others simply want to control visibility or editing functions. Unfortunately, at this time, the granularity of permissions to control the use and function at this level of detail is not included in ServiceDesk.
To provide a better understanding, it is important to understand the types of permissions in ServiceDesk. There are two types of permissions:
A. Permissions that grant you access to see objects in the portal. These are set in the USERS and GROUPS section of the ADMIN Tab. They control what you can see in the ServiceDesk Portal.
B. Permissions to work on Incidents, Changes, and Problems. When you open an Incident (process), you see those set in the lower-right side of the incident screen, This shows what groups and users can do with this case, and, if specific functions (permissions) have been set. This is the "what you can do" section, with what you were granted access to in A, above. These are call Process Permissions. See the screen shot below:
So,
The permission to EDIT COMMENT, in a Incident, is a PROCESS permission that is coupled with the ability to use the items list under the "ACTIONS" header on the screen, on the right side of the incident window. Unfortunately, permissions at this level of granularity can only be assigned on a per-incident basis, and come together. The ability to use any of the items in the Action Section and the ability to Edit Comments are joined together. If you revoke the permission, by removing the Reports.Process report permission from the individual, in the specific case where needed, he/she will not be able to perform other basic actions to incident that are relevant to their needs in a default Support I or Support II role.
Please note that when comments are edited, the history notes that the comment edit occurred, and what was changed, showing before edit, and after. This feature provides a great audit trail in the incident, if necessary, and may alleviate the need to remove this permission.
Hopefully this provides some more valuable information surrounding permissions and comments.