A brief workflow with supportive screenshot is provided below for the punch creation, completion & closure.
Note: Please follow the screenshot sequence to understand the workflow better.
The sequential workflow is given below,
1. User clicks on the [Create punch] button on the Punch list dashboard screen.
2. Data entered for a punch which is being created is shown below,
3. User (creator) will have to click on [Create Punch] button to save the punch. The punch will now be displayed on the Punch list dashboard under the My punch list tab with status as OPEN. This is shown below,
4. The creator can close the punch before it is completed. The creator, if now, clicks on the newly created punch (Status: OPEN), then the punch details are displayed with the button [Close punch item]. Hence, the creator can close the punch before receiving the completed punch if he/she chooses to do so. If the creator closes the punch before the punch is completed, the assigned user will receive notification of punch closure and accordingly the punch will be updated. Screenshot below displays a punch with status OPEN,
The assigned user will receive a notification in his registered email ID that a punch item has been assigned to him/her. Clicking the link to the punch item in the email will navigate the assigned user to the SKYSITE log-in screen. From there he/she can access his account and then navigate to the assigned punch item.
5. The Assigned user can now view the assigned punch in his SKYSITE account within the same project under the Punch list assigned to me tab with the status as OPEN. This is shown below,
Note: Since, the assigned user is selected from the 'Contacts' section (during punch creation), the assigned user is either an account user (user added as an employee in the account from the Settings > Users tab) or an external project collaborator (the project within which the punch is created is shared to the user with full access). This means that the assigned user already has access full access to the project within which the punch is created and assigned.
6. The Assigned you will be able to view the [Complete] button which he/she can press if the punch issue has been resolved. Assigned user can enter comments & associate attachments in support of his completion of the item mentioned in the punch. An assigned punch is shown below,
After assigned user enters comments and an attachment in the comments section and presses the 
button, the comment with attachment is displayed under the punch history section.
Click the [Upload and Attach] button to upload and attach a file in the comments section.
This file attached in the comment is shown below,
7. After assigned user has resolved the issue mentioned in the punch item the assigned user can click the [Complete] button. The completed punch on the Punch list dashboard under the Punch list assigned to me tab of the assigned user account is shown below,
8. A completed punch with updated status as viewed by the assigned user is shown below,
9. The punch marked as completed by the assigned user will appear with status as 'Completed' under the My punch list tab of the creator is shown in the screenshot below,
10. The creator can now close the punch (if he/she finds the punch item completion satisfactory). A completed punch as viewed by the creator is shown below,
11. After the creator clicks the [Close punch item] , the punch item will be closed. The closed punch will be displayed on the Punch list dashboard under the My Punch list tab of the creator. This is shown in the screenshot below,
Note: The punch item will appear with status closed under the Punch list assigned to me tab of the assigned user in his/her account
12. A closed punch item is displayed in the screenshot below,
Note: CC list users will only be able to view the punch items & enter comments (also attach files with the comment). These users will not be able to change the status of the punch.