Tes4Mod:Load Order

Introduction
A load order is the "date modified" ordering of your the plugins that are processed in the game from earliest to most recent, the order in which content is processed by the game engine. Active plugins are plugins loaded into the game. A plugin is installed once you put it in your data folder, but it is only active if the launcher shows that it is checked. Oblivion's launcher does not allow you to do much with your load order outside of activating and deactivating plugins. This becomes another of the motivations for installing a mod management utility (i.e, OBMM, Wrye Bash, etc.) These tools let you move plugins around (by modifying their timestamps) through a GUI, with buttons and your mouse.

Example #1 - a simple load order (with fake timestamps)
Oblivion.esm (timestamp=2006)
Progress.esm (timestamp=2007)
Unofficial Oblivion Patch.esp (timestamp=2008)
DLCShiveringIsles.esp (timestamp=2009)
Progress.esp

Once you have more than a few plugins, putting a well-structured load order together is no simple task. Even if you have only a few mods, your small load order can still be very order-dependent. There are a few rules that are forced by the game, and then there are many more rules that as a result of plugin interactions. Certain groups of mods are better off loading in certain locations in a load order because of how they overlap with other mods in that load order. First and foremost, Oblivion.esm load first. Then, all of the ESMs are loaded after it, followed by the ESPs. If a load order breaks these enforced rules, the game will throw errors and problems at the user.

Example #2 - a simple correct load order
Oblivion.esm   "A should load after B."
give priority - load after
(Ex: "Give B priority (over A.)" => "Have B load later (after A.)"
dependency (or master) - plugin a plugin depends upon 
(Ex: "A is B's dependency." => "B is a master of A." => "B modifies A."
master file - ESM

The Bash-Extended Load Order
Wrye Bash has upped the level of complexity of the Oblivion load order, in a good way (for those that use it or plan to use it.) The presence of the Bashed Patch introduces two new plugin states, merged and imported, and they allow for much greater compatibility among mods. When you rebuild the Bashed Patch (by right-clicking on it and choosing the appropriate option from the context menu) there are the groups of options: the merge menu, the import menus and the tweaks menus.

Plugins selected in the merge menu, have their content merged into the Bashed Patch. The merge is in accordance with the load order, so if two mods make changes to the same record, the latter's changes will be found in the Bashed Patch (unless some other setting in the Bashed Patch changes it, as the Bashed Patch loads latest.) The plugins does not have to be active at the time of the merge. If the plugin was not active prior to the merge or was unchecked afterward, Bash displays a plus sign in the check box, indicating that the plugin is merged. The plugin is still installed, however. There is no point leaving a merged plugin active because its changes are being completely written over by the Bashed Patch. Once you merge a plugin, deactivate it.
:Notes: 1) Bash-mergeable plugins are distinguished by green text. 2) Some Bash-mergeable mods only need to be imported, and those are often have purple-text. Those with purple text have been tagged with NoMerge.

Plugins selected in the import menu have content that meets the criteria of the specific import merged into the Bashed Patch. Again, the merge is in accordance with load order. However, only changes are imported. If a mod's records are not overwritten by other mods in the LO, those records are not being changed by anything and, thereby, will not be imported into the Bashed Patch. To ensure that a plugin's changes are imported, deactivate the plugin before rebuilding the Bashed Patch. Few mods are import-only. Those tend to be aesthetic mods (i.e., retexturers.) If a mod is not import-only (as is the case with most race mods and worldspace-affecting mods) do not deactivate it before rebuilding.
:Notes: 1) Import-only plugins are distinguished by italicized and/or purple text. 2) Some plugins that are mergeable, and even some that are not, deactivated to be import-only. If activating the Bashed Patch causes the plugin(s) to be reactivated, that is not a possibility.

Taking advantage of these extended features not only allows for greater compatibility among mods, but also allows the user to save plugins slots. Deactivated and imported mods can be ghosted (hidden from the game.) Deactivated mods do not count toward the 255 plugin cap because they are not part of the load order; however, they can still be installed. Take advantage of Bash's ghosting feature, by manually right-clicking on plugins and selecing the option from the context menu or by setting auto-ghost in the   header context menu. Other features of Bash that make it a very helpful LO management tool are 1) the Lock Times features, also available through the   header context menu, that, when activated, prevents installation of new plugins from messing up the load order and 2) the check box colors that indicate whether a plugin's masters are present, missorted or missing (which is okay only for plugins with the Filter tag.) There is not tool that gives the users as much information about the state of their load orders, and, for Obilvion, that is quite important.


Load Order Template
based on the BOSS masterlist ...
# Oblivion.esm
# ESMs (see ReadMes)
# Early-Loading Mods (see ReadMes)
## NPC Faces
## Vanilla Fixes - miscellaneous fixes, UOP, etc.
## SI - miscellaneous fixes, USIP, etc.
## Fran files for FCOM
### Base Mods - library mods, new content mods, etc.
### Environmental Mods - weather, water tweaks, sound, lighting
### Mods that can be overwritten or add new content
### UI mods - Map Marker tweaks, Hotkey mods
## DLCs I - Horse Armor, Orrery, Vile Lair, Mehrunes, Spell Tomes
## Body replacers
# Items
## Early loaders (see ReadMes)
## New items
## Armor and clothing replacers for body replacers
# Pre Overhaul (see ReadMes)
## Mods with specific conflicts
## Mods that change names (that can use the Import Names Bash tag)
## DLCs II - Thieves Den
# Overhauls (See ReadMes for specific load ordering information)
## Fran options
## FCOM and OOO support mods
## OOO
## MMM & FCOM (main)
## MMM & FCOM options (must see ReadMes for specific load ordering info)
## Other overhaul-compatible mods
## Overhaul immediate override patches
# Post Overhaul (see ReadMes)
# Quests and Locations
# FCOM quest compatibility patches
# More quests (See ReadMes)
# Landscape and City aesthetics
## Unique Landscapes
## Mods that have to load after ULs and before city overhaul mods
## Open Cities
## Quests that have to load after OC and ULs
## Overrides
### Harvest Flora
### Other visual improvements (i.e., Better XX)
### Realism
### Vampires
### Magic
### Combat
### Skills, Attributes and Leveling
### Poses and animations
### Late loading overrides - darkening mods, Item Interchange
### Cosmetic mods and race rebalancers
### Companions
### Post BC and OBC
### Message suppression
### Respawn & Day length overrides (most made obsolete by bashed patch)
### Shader mods
# Pre Bash (See ReadMes)
# Bashed Patch
# Post Bash (See ReadMes)
## Most Duke Patrick mods
## Last Files
### Land Magic
### Map changing mods
### Stability mods (scripts) - FormID Finder, Kuertee Actor Details, Clean up, Clean quit, OGE Support, Streamline (last)

Load Order Management Utilities
BOSS automatically orders more than 10000 plugins, and it will save the user a ton of work when it comes time to perfect an load order. After running BOSS, it will place plugins that it does not recognize at the bottom of your load order and those should be moved by hand with Wrye Bash before launching the game and/or updating Bashed Patches.

#BOSS


See Also
BOSS
How to Post Your Load Order
Wrye Bash