Trail signs & Secret language

[Mingus]

With the advent of writing in the language you are speaking. Could rangers get, with a little coding so you can write on the ground, the ability to make trails signs. ie Piled up rocks, tied together grass reeds, laid sticks and limbs in simple patterns, ect , ect. To relay a short message to others that walk the same path. Like how the thieves cant works, this is only readable by ranger(maybe druids) but unlike the cant the message si not seen in the present and its only in a writing format. Like the boards, the messages would have to be made to last even over a reboot but have a timer so they eventually dissapear and aswell as others being able to remove them. Also like all other ranger skills, this should only work outdoors.(and the underdark)

[Mingus]

The Secret Language

All druids can speak a secret language in addition to other tongues they know. Using the optional proficiency system, the secret language does not require a proficiency slot.

The secret language of the druids has its roots in British tradition. A language called Thari, derived from Celtic roots, apparently was spoken as a secret tongue throughout the British Isles by a small number of traveling folk such as tinkers and bards. It later was adopted by some Gypsy clans in addition to Romany, their own Indic language. Thari may predate the Dark Ages, and some claim fluency in it even today. Certain researchers seeking the roots of Thari as a language distinct from Gaelic have linked its origins to both ancient Celtic craft guilds and to the historical druids. If the DM wants to name the druids' secret language, Thari possesses some historical relevance.

Not only can druids use the secret language to provide passwords, they can speak this private tongue when they wish to baffle nondruidic eavesdroppers. It is a precise tool for discussing Nature; a druid can say "dense, old-growth pine forest" in one word rather than a whole phrase.
The secret language has a specialized and detailed vocabulary limited to dealing with Nature and natural events; beyond this sphere, it is very basic. A druid could use the secret language to talk about the health of a person, animal, or plant; discuss the weather; or give detailed directions through the wilderness. The language also can describe druidic spells, ceremonies, powers, and any natural and supernatural creatures known to the druids. However, it contains no words for sophisticated human emotions, for most tools or artifacts (beyond those used for hunting, farming, or fishing), or for weapons and armor (other than items druids use). The language also contains few words that refer to concepts peculiar to sentient beings, like property, justice, theft, or war. Tense distinctions blur in this secret tongue; usually the concepts druids express bear a certain immediacy or timelessness.
Finally, the secret language of the druids remains a purely spoken tongue. A few simple runes or marks (symbolizing danger, safe water, safe trail, and so on) exist for marking paths and leaving messages, but the language cannot communicate actual sentences and complex ideas in writing.
Here's an example of how the secret language works in practice. Suppose two druids are discussing a magical item and want to converse entirely in the secret language, using no words borrowed from other tongues. One druid wishes to say:

This magical long sword was a gift to Melinda, wife to King Rupert, from Rupert's court wizard Drufus. The mage gave it the power to throw lightning bolts. But then King Rupert grew jealous of Melinda. He had her executed and took the blade for himself. After Rupert died, the sword was left buried in the dungeons under his castle.

In the secret language, the story might come out something like this:

This magic scimitar was for the Tall Golden Female, mate of the Man-Leader, from the Wielder of Magic from the Vale of the White Eagles. He put the call lightning power in it. But the Man-Leader wanted it. He killed the Tall Golden Female and took it for himself. He died. The scimitar stayed in the cave under his big stone man-den.

See the difference? There's no word for long sword, so our druid has substituted "scimitar." (All druidic weapons have names.) The idea of a gift is described in more basic terms. In addition, the concept of naming has no place in this Nature-oriented language; people and creatures are known by description, status, or place of origin.
Wizard becomes the more generic "wielder of magic." Lightning, a natural phenomenon, has an equivalent in the secret language. But the secret language cannot convey a human emotion such as Rupert's jealousy, so the druid has had to substitute less precise phrasing. Similarly, the private tongue does not cover execution or murder, so the druid used the more generic "killed." Finally, no druidic term corresponds to dungeon or castle, so the druid has had to use other words"cave under his big stone man-den"--to convey that image. Of course, a druid not worried about being overheard might mix the secret language and normal speech in a single sentence.
In a SpelljammerÆ or PlanescapeÆ campaign and through the use of certain spells and magical items, druids from different worlds can meet. The DM should decide whether their secret languages resemble each other enough to allow communication.
Finally, the druid's secret language, while private, is not supernatural--theoretically, others can learn it. However, because the tongue provides druids with code phrases or passwords, they simply will not teach it to nondruids. The great druid of the region will punish any who break with this tradition.

Are there resources for a new language to be added and maybe made like thieves cant.

The part about passwords could be made so that you have to be speaking it to cast certain spells or order elemtals about or shapechange or other things of just druidic nature.