why my custom site column have 2 different internal names on the Site Level & on the List level

Question

I have created a site column of type "People or Group" and i name it "Software Development Risk/Issue Owner". now i added this site column inside multiple lists. now i find this confusing issue.

when i access the site column from the site level i inspected the following Internal name Software_x0020_Development_x0020_Risk_x002F_Issue_x0020_Owner from the URL :-

/_layouts/15/ManageContentTypeField.aspx?ctype=0x0103004AFB52A22B74934CB139F46F5A802B7505&Field=Software%5Fx0020%5FDevelopment%5Fx0020%5FRisk%5Fx002F%5FIssue%5Fx0020%5FOwner&Fid=

while when i access the site column from one of the list levels, i inspected the following Internal name Software_x0020_Development_x0020 from the URL :-

/_layouts/15/FldEditEx.aspx?CloseOnCancel=1&List={60F9B143-EBA4-47C6-B714-3AA863B26AAC}&Field=Software%5Fx0020%5FDevelopment%5Fx0020&Source=

so my First question is why the site column have 2 different internal names ; one at the site level while the other at the list level ?

Second question, now i wanted to move some items from one list named "Action" to another list named "Risk Issue" , using the following power-shell script :-

$web = get-spweb "http://*****/teamsites/SoftwareDevelopment/"
$list = $web.lists["Action"]
$list2 = $web.lists["Risk Issue"]
foreach ($i in $list.items)
{
$a = $i["ID"];
$sourceItem = $list.items.GetItemById($a)

$versions = $sourceItem.versions;

$newItem = $list2.items.Add();

$versionCount = $versions.Count;

##We need a for loop here as we must work backwards through the version collection
for ($i = $versionCount;$i -gt 0;$i--)
{
    $version = $versions[$i-1];


    $newItem["Title"] = $version["Title"];
    ##code goes here.....
    $newItem["Software_x0020_Development_x0020_Risk_x002F_Issue_x0020_Owner"] = $version["Software_x0020_Development_Manager"];


    $newItem.Update();

}
}

but i got this exception :-

Column 'Software_x0020_Development_x0020_Risk_x002F_Issue_x0020_Owner' does not exist. It may have been deleted by another user. At line:21 char:5 + $newItem["Software_x0020_Development_x0020_Risk_x002F_Issue_x0020_Owner"] = ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~ + CategoryInfo : OperationStopped: (:) [], ArgumentException + FullyQualifiedErrorId : System.ArgumentException

now if i replace this $newItem["Software_x0020_Development_x0020_Risk_x002F_Issue_x0020_Owner"] with this $newItem["Software_x0020_Development_x0020"] (in other words i used the list level internal name instead of the site level internal name ) the exception will disappear .. so what is causing this? i always reference the site columns as defined inside the site level,, not sure why in this case i can not do so ?

can anyone adivce on this please ?

-----------EDIT-------

For my second question i did the following test . Here my test for 3 columns:-

1) First Column have its internal name at the list level = "DueDate", while at the site level its internal name = "TaskDueDate".

2) Second Column have its internal name at the list level = "Technical_x0020_Delivery_x0020_T", while at the site level its internal name = "Technical_x0020_Delivery_x0020_Team".

3) Third Column have its internal name at the list level = Software_x0020_Development_x0020, while at the site level its internal name = Software_x0020_Development_x0020_Risk_x002F_Issue_x0020_Owner.

now on the first and third site columns i was NOT able to reference the columns using their site level internal names as shown below, as i will get an error inside the powershell windows that it can not find these columns

$newItem["TaskDueDate"]

&

$newItem["Software_x0020_Development_x0020_Risk_x002F_Issue_x0020_Owner"]

and i have to use their internal names as defined inside the list level (not site level), so this will not raise an error:-

$newItem["DueDate"]

&

$newItem["Software_x0020_Development_x0020"]

while for the second column i was able to reference it either using its site level or list level internal names.. so can anyone adivce what is the rule that govern this ?

Answer 1

Very long column names are truncated to 32 characters at the list level. That even happens when you create a column in the list that is not based on an existing site column.

Try it. Create a column with a name that has more than 32 characters, for example aaaaabbbbbcccccdddddeeeeefffffggggghhhhh. Then edit the column and look at the URL. Only the first 32 characters show up.

http://sharepoint/_layouts/FldEdit.aspx?List=%7B7E1CF10A%2D52C2%2D4D85%2DBFD5%2D7DA851FE248D%7D&Field=aaaaabbbbbcccccdddddeeeeefffffgg

Software_x0020_Development_x0020 has exactly 32 characters. The rest of the column name is truncated.

Spaces and other special characters like dashes, underscores, slash etc, further muddy the waters with the %20 etc.

So, the answer is: keep the column names shorter than 32 characters.

Answer 2

Using a site column in a list effectively makes a copy of the site column and turns it into a list column. You can then make changes to the column within the list. For example, if your site column is a Choice field, and your choices are A and B, in the list you can change the choices in the column to be A, B, and C without affecting the site column. You can then change the site column and indicate whether you want those changes to propagate to the inheriting column in your list.

The internal column name in your case was truncated because the name of your site column is so long.