# Saving subduction zone polarity attribute in shapefile
**URL:** https://discourse.gplates.org/t/saving-subduction-zone-polarity-attribute-in-shapefile/646
**Category:** Q&A
**Created:** [22 February 2023 16:30 UTC](https://discourse.gplates.org/t/saving-subduction-zone-polarity-attribute-in-shapefile/646 "2023-02-22T16:30:10Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@thomas.schouten](https://discourse.gplates.org/u/thomas.schouten)
#### Post date: [22 February 2023 16:30 UTC](https://discourse.gplates.org/t/saving-subduction-zone-polarity-attribute-in-shapefile/646/1 "2023-02-22T16:30:10Z")
Hi,
For my reconstruction I am building closing plate polygons. I have a .shp with a set of polylines that define a subduction zone. I want to indicate the polarity of said subduction using the gpml:SubductionZonePolarity attribute. However, when I save the shapefile and restart GPlates, the file has lost the attribute “gpml:SubductionZonePolarity”. However, I can save this information when I save it as a .gpml file.
Q: Is it in general not possible to assign attributes such as subduction polarity to a .shp file? Are there any other attributes of other plate boundaries (i.e. transforms and mid-ocean ridges) that I should be aware of that are not saved in a .shp file?
Many thanks,
Thomas
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### Author:  [@john.cannon](https://discourse.gplates.org/u/john.cannon)
#### Post date: [24 February 2023 02:42 UTC](https://discourse.gplates.org/t/saving-subduction-zone-polarity-attribute-in-shapefile/646/2 "2023-02-24T02:42:14Z")
For topological closed plate boundaries/networks it’s best to use the native `GPML` format when possible (which records the complete set of feature properties).
The attributes stored in Shapefiles are listed [here](https://www.gplates.org/docs/user-manual/Shapefiles/). These only include the most common feature properties such as time period, name/description, plate ID (and optional conjugate). And for half-stage spreading of mid-ocean ridges there’s left/right plate IDs and spreading asymmetry. But yeah, subduction polarity is not included in that.
There is work planned, for a future GPlates release, to bring Shapefiles (and other non-native file formats) more in line with the [GPlates Geological Information Model](https://www.gplates.org/docs/gpgim/).