cisco release designation definitions

From https://www.cisco.com/public/library/iosplanner/reldesignation.html

Normally only install GD deployments as they are considered stable. Usually a version or two behind the latest release. Only use LD and ED to patch a specific bug or issue. These versions are more likely to contain bugs.

Release Designations Defined 

Deferral (DF) The purpose of the Deferral Advisory is to announce the removal of affected IOS image(s) from Cisco's offerings (i.e.CCO) and to introduce its replacement IOS image(s). At the time that the Deferral of an IOS image is advised, customers are strongly urged to migrate from the affected image(s) to the replacement image(s). Early Deployment (ED)  Software releases that provide new features and new platform support in addition to bug fixes. Cisco IOS CTED, STED, SMED, and XED are variations of ED software releases. Maintenance Deployment (MD)  A Cisco software release that provides bug fix support and ongoing software maintenance. General Deployment (GD)  Date at which this software release reached the "General Deployment" milestone in its lifecycle. A Major Release of Cisco IOS software reaches the "General Deployment" milestone when Cisco feels it is suitable for deployment anywhere in customer networks where the features and functionality of the release are required. Criteria for reaching the "General Deployment" milestone are based on, but not limited to, customer feedback surveys from production and test networks using the releases, CE bug reports, and reported field experience. Only Major Releases are candidates to reach the General Deployment milestone. Note: GD will not be applied to any future Cisco IOS Software maintenance releases or rebuilds starting from Cisco IOS Software Release 12.4. Please refer to the Cisco IOS Software General Deployment (GD) Program Retirement Product Bulletin for more information:http://www.cisco.com/en/US/prod/collateral/iosswrel/ps8802/ps6968/ps6350/product_bulletin_cisco_ios_software_gd_program_retirement.html. Limited Deployment (LD)  A Major Release of Cisco IOS software is said to be in the "Limited Deployment" phase of its lifecycle during the period between initial FCS and the General Deployment (GD) milestones. Note:LD will not be applied to any future Cisco IOS Software maintenance releases or rebuilds starting from Cisco IOS Software Release 12.4. Please refer to the Cisco IOS Software General Deployment (GD) Program Retirement Product Bulletin for more information:http://www.cisco.com/en/US/prod/collateral/iosswrel/ps8802/ps6968/ps6350/product_bulletin_cisco_ios_software_gd_program_retirement.html.