attaching key-value pairs to geometry

I'm curious if there is a way to attach attributes to geometry in Rhino, and then see them in Grasshopper. Like a list of key-value pairs. This might be unclear, so here is an example:

I have many curves in Rhino that represent property lines on a city map. I want to add data attributes to the curves, such as zoning type, appraised tax value, and other property data. I want to use the data for use in geometric analysis on the properties, such as how much residential zoning is within a certain proximity of commercial zoned properties.

I was figuring I'd just feed the data into primitive components and run the data in parallel with the geometries, but this seems like an ugly solution that would result in a lot of components and work.

I also considered using the GUIDs to refer to an external table such as a CSV file, but was unsure about the parsing code for the Read File component. This is probably the way to go. But it seems like the Read File component only has one output, so I'd probably just need multiple ReadFiles for each data field.

Any ideas? Or location of good Read File parsing code?