# Plain and keyword signature
**URL:** https://discourse.cmake.org/t/plain-and-keyword-signature/4720
**Category:** Usage
**Tags:** os:linux
**Created:** [December 20, 2021, 10:08am UTC](https://discourse.cmake.org/t/plain-and-keyword-signature/4720 "2021-12-20T10:08:51Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@s0n1c](https://discourse.cmake.org/u/s0n1c)
#### Post date: [December 20, 2021, 10:08am UTC](https://discourse.cmake.org/t/plain-and-keyword-signature/4720/1 "2021-12-20T10:08:51Z")
Hello everyone,
by now I thought to get along with CMake pretty good but there are still some things I am doing wrong. When using it in my current project it gives the error message:
CMake Error at CMakeLists.txt:63 (target\_link\_libraries):
The plain signature for target\_link\_libraries has already been used with
the target “target\_name”. All uses of target\_link\_libraries with a
target must be either all-keyword or all-plain.
Can anyone help me with that?
I am grateful for any kinds of help.
s0n1c
---
### Author:  [@marc.chevrier](https://discourse.cmake.org/u/marc.chevrier)
#### Post date: [December 20, 2021, 1:50pm UTC](https://discourse.cmake.org/t/plain-and-keyword-signature/4720/2 "2021-12-20T13:50:30Z")
`all-plain` means using `target_link_libraries()` command **without** keywords (i.e. `PUBLIC`, `PRIVATE`, etc…). `all-keyword` is the reverse: `target_link_libraries()` is used with keywords.
You cannot, for the same target, mix the two signatures. As soon as `target_link_libraries()` command is called on a target with a signature, all other next calls, on the same target, must use the same signature.