Sometimes you develop some SharePoint application that needs to modify/change data in Lists/Doclibs.
Sometimes you being lazy and just use the title/display name of the field ( SPList.Fields["Title"] ) option in order to get the right field you want to work on.
So sometimes you are being wrong.
Even though it will work great, it won't work in any language.
2 options you have then - Internal name ( which usually will be enough but problematic when it comes for columns with similar name, such as "Modified" and "Modified By" ) or GUIDs ( because the OOB fields have const guids for any list ).
So just have a look on that and start working better ( and support any language ).
Internal Name :
Created By : Author
Modified : Modified
Modified By : Editor
Has Copy Destinations : _HasCopyDestinations
Copy Source : _CopySource
Approval Status : _ModerationStatus
Approver Comments : _ModerationComments
URL Path : FileRef
Path : FileDirRef
Modified : Last_x0020_Modified
Created : Created_x0020_Date
File Size : File_x0020_Size
Item Type : FSObjType
Effective Permissions Mask : PermMask
ID of the User who has the item Checked Out : CheckedOutUserI
Is Checked out to local : IsCheckedoutToLocal
Checked Out To : CheckoutUser
Name : FileLeafRef
Unique Id : UniqueId
ProgId : ProgId
ScopeId : ScopeId
Virus Status : VirusStatus
Checked Out To : CheckedOutTitle
Check In Comment : _CheckinComment
Checked Out To : LinkCheckedOutTitle
Document Modified By : Modified_x0020_By
Document Created By : Created_x0020_By
File Type : File_x0020_Type
HTML File Type : HTML_x0020_File_x0020_Type
Source Url : _SourceUrl
Shared File Index : _SharedFileIndex
Edit Menu Table Start : _EditMenuTableStart
Edit Menu Table End : _EditMenuTableEnd
Name : LinkFilenameNoMenu
Name : LinkFilename
Type : DocIcon
Server Relative URL : ServerUrl
Encoded Absolute URL : EncodedAbsUrl
Name : BaseName
File Size : FileSizeDisplay
Property Bag : MetaInfo
Level : _Level
Is Current Version : _IsCurrentVersion
Select : SelectTitle
Select : SelectFilename
Edit : Edit
owshiddenversion : owshiddenversion
UI Version : _UIVersion
Version : _UIVersionString
Instance ID : InstanceID
Order : Order
GUID : GUID
Workflow Version : WorkflowVersion
Workflow Instance ID : WorkflowInstanceID
Source Version (Converted Document) : ParentVersionString
Source Name (Converted Document) : ParentLeafName
Title : Title
Template Link : TemplateUrl
Html File Link : xd_ProgID
Is Signed : xd_Signature
Merge : Combine
Relink : RepairDocument
GUIDs :
ID : 1d22ea11-1e32-424e-89ab-9fedbadb6ce1
Content Type ID : 03e45e84-1992-4d42-9116-26f756012634
Content Type : c042a256-787d-4a6f-8a8a-cf6ab767f12d
Created : 8c06beca-0777-48f7-91c7-6da68bc07b69
Created By : 1df5e554-ec7e-46a6-901d-d85a3881cb18
Modified : 28cf69c5-fa48-462a-b5cd-27b6f9d2bd5f
Modified By : d31655d1-1d5b-4511-95a1-7a09e9b75bf2
Has Copy Destinations : 26d0756c-986a-48a7-af35-bf18ab85ff4a
Copy Source : 6b4e226d-3d88-4a36-808d-a129bf52bccf
Approval Status : fdc3b2ed-5bf2-4835-a4bc-b885f3396a61
Approver Comments : 34ad21eb-75bd-4544-8c73-0e08330291fe
URL Path : 94f89715-e097-4e8b-ba79-ea02aa8b7adb
Path : 56605df6-8fa1-47e4-a04c-5b384d59609f
Modified : 173f76c8-aebd-446a-9bc9-769a2bd2c18f
Created : 998b5cff-4a35-47a7-92f3-3914aa6aa4a2
File Size : 8fca95c0-9b7d-456f-8dae-b41ee2728b85
Item Type : 30bb605f-5bae-48fe-b4e3-1f81d9772af9
Effective Permissions Mask : ba3c27ee-4791-4867-8821-ff99000bac98
ID of the User who has the item Checked Out : a7b731a3-1df1-4d74-a5c6-e2efba617ae2
Is Checked out to local : cfaabd0f-bdbd-4bc2-b375-1e779e2cad08
Checked Out To : 3881510a-4e4a-4ee8-b102-8ee8e2d0dd4b
Name : 8553196d-ec8d-4564-9861-3dbe931050c8
Unique Id : 4b7403de-8d94-43e8-9f0f-137a3e298126
ProgId : c5c4b81c-f1d9-4b43-a6a2-090df32ebb68
ScopeId : dddd2420-b270-4735-93b5-92b713d0944d
Virus Status : 4a389cb9-54dd-4287-a71a-90ff362028bc
Checked Out To : 9d4adc35-7cc8-498c-8424-ee5fd541e43a
Check In Comment : 58014f77-5463-437b-ab67-eec79532da67
Checked Out To : e2a15dfd-6ab8-4aec-91ab-02f6b64045b0
Document Modified By : 822c78e3-1ea9-4943-b449-57863ad33ca9
Document Created By : 4dd7e525-8d6b-4cb4-9d3e-44ee25f973eb
File Type : 39360f11-34cf-4356-9945-25c44e68dade
HTML File Type : 0c5e0085-eb30-494b-9cdd-ece1d3c649a2
Source Url : c63a459d-54ba-4ab7-933a-dcf1c6fadec2
Shared File Index : 034998e9-bf1c-4288-bbbd-00eacfc64410
Edit Menu Table Start : 3c6303be-e21f-4366-80d7-d6d0a3b22c7a
Edit Menu Table End : 2ea78cef-1bf9-4019-960a-02c41636cb47
Name : 9d30f126-ba48-446b-b8f9-83745f322ebe
Name : 5cc6dc79-3710-4374-b433-61cb4a686c12
Type : 081c6e4c-5c14-4f20-b23e-1a71ceb6a67c
Server Relative URL : 105f76ce-724a-4bba-aece-f81f2fce58f5
Encoded Absolute URL : 7177cfc7-f399-4d4d-905d-37dd51bc90bf
Name : 7615464b-559e-4302-b8e2-8f440b913101
File Size : 78a07ba4-bda8-4357-9e0f-580d64487583
Property Bag : 687c7f94-686a-42d3-9b67-2782eac4b4f8
Level : 43bdd51b-3c5b-4e78-90a8-fb2087f71e70
Is Current Version : c101c3e7-122d-4d4d-bc34-58e94a38c816
Select : b1f7969b-ea65-42e1-8b54-b588292635f2
Select : 5f47e085-2150-41dc-b661-442f3027f552
Edit : 503f1caa-358e-4918-9094-4a2cdc4bc034
owshiddenversion : d4e44a66-ee3a-4d02-88c9-4ec5ff3f4cd5
UI Version : 7841bf41-43d0-4434-9f50-a673baef7631
Version : dce8262a-3ae9-45aa-aab4-83bd75fb738a
Instance ID : 50a54da4-1528-4e67-954a-e2d24f1e9efb
Order : ca4addac-796f-4b23-b093-d2a3f65c0774
GUID : ae069f25-3ac2-4256-b9c3-15dbc15da0e0
Workflow Version : f1e020bc-ba26-443f-bf2f-b68715017bbc
Workflow Instance ID : de8beacf-5505-47cd-80a6-aa44e7ffe2f4
Source Version (Converted Document) : bc1a8efb-0f4c-49f8-a38f-7fe22af3d3e0
Source Name (Converted Document) : 774eab3a-855f-4a34-99da-69dc21043bec
Title : fa564e0f-0c70-4ab9-b863-0177e6ddd247
Template Link : 4b1bf6c6-4f39-45ac-acd5-16fe7a214e5e
Html File Link : cd1ecb9f-dd4e-4f29-ab9e-e9ff40048d64
Is Signed : fbf29b2d-cae5-49aa-8e0a-29955b540122
Merge : e52012a0-51eb-4c0c-8dfb-9b8a0ebedcb6
Relink : 5d36727b-bcb2-47d2-a231-1f0bc63b7439
