The "_options_edit_url" is a line item property that is created when the customer adds a product that contains custom options to the cart.
When a custom item is added to the cart, the app creates a snapshot of the selections that are made and creates a unique link that can be used to visit the product page with the selections prefilled.
For Customers:
The cart template can be updated so that each custom item includes an "Edit Options" button, When clicked, the customer will go back to the product page and the options will be prefilled in with what was selected previously. The customer can then edit the selections and re-add the product to the cart.
Below is an example snippet that shows how to add the edit link to the cart.
{%- for p in properties -%}
{% if p.first == "_options_edit_url" %}
<a href='{{p.last}}'>Edit Options</a>
{% endif %}
{%- endfor -%}
For Merchants:
This link can be used from the order detail page in the Shopify admin to open the product page and double check the selections that were made by the customer.
Disable The Options Edit Url:
This option can be disabled in the app settings by selecting the "Disable Cart Edit Link" option.