dropdown - How to accept multiple types of input to a table cell?

I have a problem with a column in a table in which the cells may receive data in multiple ways:

1. You may write a number, say 1.0. If you write you can only write numbers.


2. 
   

   Place an object in the cell, say abc either by:

   
   
   
   
   • dragging and dropping object from a list and drop it on cell.
   
   
   • selecting it from a drop down.
   
   
   
   

   The objects can not be numbers. They have names to uniquely identify them.

   
   
   

I have tried to illustrate some possible choices with some crappy drawings below:

1. 
   

   A separate column A contains drop down box with choices:

   
   
   
   
   • enter constant
   
   
   • drop object
   
   
   • select from list
   
   
   
   
   

   A choice in this drop down will affect how you interact with the cells in column B.

   
   


2. Similar to above except we combine the drop down and edit field into one cell. So we don't have two columns. This avoids problems with the two related columns being separated because user rearranges the columns e.g.

Are there any standards for this, or any well known applications which do something similar anywhere?

Some context

Think of this as a sort of 3D modeling application. You are specifying some upper and lower boundary in a 3D world. These upper and lower boundaries can be given as a Z value (a number) or by a geometric shape. If you specify a geometric shape you have to do that by name in a list or drag and drop.

^{download bmml source – Wireframes created with Balsamiq Mockups}

Basically I want something that works as below, but which will fit nicely into a table. What the mockup shows is that there are 3 mutually exclusive ways to specify a distance. Distance can be between two completely flat surfaces, in which case it is enough to specify a Z value. Then the distance is the same regardless of X, Y coordinate. Or you can specify a surface of any shape, in which case the distance between the surfaces will vary depending on X, Y.

^{download bmml source}